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PROCEEDINGS 

OF THE 

WASHINGTON ACADEMY OF SCIENCES 

Vol. 1, pp. 15-106 May 9, 1899 



REVISION OF THE SQUIRRELS OF MEXICO 
AND CENTRAL AMERICA 



E. W. NELSON 



WASHINGTON, D. C. 
Published by the Academy 
1S99 



^33(,n 



,/ 




PROCEEDINQS 

OF THE 

WASHINGTON ACADEMY OF SCIENCES 

Vol. I, pp. 15-110. May, 9, 1899. 



REVISION OF THE SQUIRRELS OF MEXICO AND 
CENTRAL AMERICA.^ 

By E. W. Nelson. 

CONTENTS. 

Introduction P- ^5 

Physiography of the Region i7 

History and Nomenclature ^° 

Notes on Distribution and Variation 20 

Subgenera of North American Squirrels 23 

Key to Species 33 

List of Species with Type Localities 36 

Systematic Descriptions of Species 3^ 

INTRODUCTION. 

The arboreal squirrels inhabiting the region between the 
southern border of the United States and the Isthmus of Pan- 
ama have been studied by several authors, notably J. E. Gray, 
E. R. Alston and J. A. Allen, The material at the disposal of 
these revisers was of the most fragmentary character, often 
without definite localities and in poor condition, hence it is 
hardly surprising that their conclusions are unsatisfactory. 

During the past few years the quantity of material has been 
greatly increased and its quality much improved. Mr. G. K. 
Cherrie and Senor Anastacio Alfaro in Costa Rica; Dr. Chas. 
W. Richmond in Nicaragua ; Mr. A. Forrer, the Lumholtz Ex- 
pedition, and the late Dr. Audley C. Buller in Mexico, and 
Dr. E. A. Mearns, U. S. A., on the Mexican Boundary, have 

1 Recommended for publication by the Biological Society of Washington, 
February 25, 1S99. 

Proc. Wash. Acad. Sci., May, 1S99. (15) 



l6 NELSON 

contributed largely to the extent and value of recent collections. 
The bulk of new material, however, has been gathered by 
Mr. E. A. Goldman and myself. Since 1891 we have been 
engaged in making explorations for the United States Bio- 
logical Survey, under the Department of Agriculture. Western 
Guatemala has been explored and Mexico has been repeatedly 
traversed from north to south and from sea to sea. The routes 
of nearly every naturalist whose work is recorded have been fol- 
lowed, and almost all the known type localities of Mexican mam- 
mals have been visited. The series of squirrels thus brought 
together has given an insight into the relationships of the mem- 
bers of this group, which lack of material had hitherto rendered 
impossible. Moreover, familiarity with the topography of the 
country and the geographic distribution of Mexican and Guate- 
malan species gave me advantages not possessed by any pre- 
vious worker on Neotropical squirrels.^ 

During the preparation of the present revision I have been 
able to examine representatives — and in most cases types or topo- 
types — of nearly all the known species and subspecies found 
in Mexico and Central America. Dr. C. Hart Merriam, who 
had already done some work on the group, generously placed 
in my hands his MS notes and the Biological Survey series 
of more than 600 specimens ; Mr. F. W. True, Executive 
Curator of the U. S. National Museum, gave me the use of the 
National Museum series, and Dr. J. A. Allen, Curator of Mam- 
mals in the American Museum of Natural History, forwarded 
the Tropical American squirrels, including the types of his spe- 
cies, in that collection. These additions brought the total num- 
ber of specimens up to 919. But after a little study it be- 
came evident that, in order to reach satisfactory conclusions on 
many questions of synonymy, definite information was necessary 
concerning the types of species described by Gray and others. 
Accordingly, a series of specimens from the U. S. National 
Museum and Biological Survey collections answering as closely 
as possible to the imperfect published descriptions, was sent to 
Mr. Oldfield Thomas, Curator of Mammals in the British Mu- 
seum, for comparison with the types preserved in London. Mr. 

ij am especially indebted to Dr. T. S. Palmer for n\any valuable suggestions, 
particularly in connection with the nomenclature and synonymy. 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 1 7 

Thomas responded very handsomely, devoting considerable 
time to the comparison and returning the specimens with an- 
notations which have made it possible to state authoritatively 
exactly what species were represented. 

Within the area covered by the present paper Gray, in 1867, 
recognized 18 species and varieties, Allen in 1877, 6 species and 
3 varieties, and Alston in 1880, only 7 species. As a result of 
the accumulation of modern material a number of new forms 
have been described by various authors, and in the present re- 
vision 43 species and subspecies are recognized. ^ In order to 
understand the relationships of these numerous species it is 
necessary to have a general idea of their surroundings and the 
topographic features of the region they inhabit. 

PHYSIOGRAPHY OF THE REGION. 

Mexico and Central America present great contrasts of topo- 
graphic and climatic conditions, accompanied by wonderful 
variety of animal and vegetable life. The mountain ranges 
fronting the two coasts of Mexico, and uniting near the Isthmus 
of Tehuantepec, are of great magnitude and form the outer 
border or rim of the broad interior tableland. Southward the 
continental area is narrow and the elevated interior correspond- 
ingly reduced. One of the most characteristic features is the 
comparatively level lowland skirting both coasts between the 
sea and the base of the mountains. This coastal plain is some- 
times 100 miles wide and often broken by hills or low ranges 
of mountains which extend out from the main interior ranges as 
short spurs, or rise island-like in the midst of the plain. The 
hills reach the sea at many points but usually the country near 
shore is level. The northern parts of the coastal plains, except 
a very narrow belt along the east shore of Mexico, lie within 
the Lower Sonoran zone and in passing southward, gradually 
merge into the Arid Tropical. On the west side the arid char- 
acter of the coast belt extends at least to Costa Rica, but on the 
east coast it gives way in the southern half of Vera Cruz to the 
Humid Tropical zone which, with the exception of the arid 

^ Several South American species have been reported from the Isthmus of 
Panama but in the absence of any material have necessarily been omitted. 



l8 NELSON 

tropical peninsula of Yucatan, continues on to the Isthmus 
of Panama. The Arid Tropical areas are characterized by low 
scrubby forests ; the Humid Tropical by greater luxuriance of 
vegetation. The rainfall on the mountain slopes facing the sea 
on both coasts is much heavier than on the adjacent lowlands, 
and is distributed more generally throughout the year, produc- 
ing a heavier forest growth. In eastern Mexico this Causes a 
northward extension of the Humid Tropical area, in the form of a 
long narrow tongue along the mountains, which reaches eastern 
San Luis Potosi. On the west coast the uniformity of the Arid 
Tropical area is broken by humid tropical islands at intervals 
along the mountains northward nearly to the border of Guer- 
rero, and by belts of heavy forest along streams flowing through 
the plains. 

Above the Tropical zones in Mexico the higher mountain 
slopes extend through all the succeeding life zones to extreme 
timberline, and in Central America to altitudes varying from 
6000-14,000 feet. Differences of altitude are always accom- 
panied by climatic changes, but in addition local causes also 
often exert a marked influence. Thus the proximity of high 
mountains, or the trend of a range or spur in relation to the 
course of the prevailing wind, frequently has a direct effect 
upon the rainfall of the surrounding district. In Vera Cruz 
the north and northeast slopes of mountains are by far the most 
humid owing to the fact that during the dry winter months 
' northers ' prevail, bringing fogs and rain. A striking example 
of the climatic differences that may exist within a limited area 
is afforded by the slopes of Mt. Orizaba, in western Vera Cruz. 
The top of this mountain rises over 18,000 feet above sea level 
and is perpetually covered with snow ; its southeastern base 
reaches the hot coast plain, and at an altitude of 800 feet the 
foothills are covered with a humid tropical forest so dense in 
places that the dew drops all day from the undergrowth ; while on 
the opposite side, at an altitude of 8000 feet, lie the arid treeless 
tablelands. 

HISTORY AND NOMENCLATURE. 

The first tree squirrel of tropical North America to receive 
a distinctive scientific name was Sciuriis atireogaster, described 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA I9 

by F. Cuvier in 1829. During the succeeding decade a few 
species were described, and in 1839 Bachman^ published sev- 
eral additional species from Mexico. The first general enumera- 
tion of Tropical American squirrels appeared in 1842 in Les- 
son's ' Nouveau Tableau du Regne Animal,' in which seven 
species were mentioned from the region under consideration. 
During the next 25 years Wagner, Schinz, Peters, and Gray 
described a few species, Audubon and Bachman gave ac- 
counts of several in their * Quadrupeds of North America ' 
(1851-54), and Baird in 1857 referred briefly to the Mexican and 
Central American species in his ' Mammals of North America.' 
The year 1867 was marked by the publication of two papers, 
Fitzinger's ' Natiirliche Anordnung der Nagethiere,'"^ which 
included 10 species and subspecies of squirrels from Tropical 
North America ; and, a few months later, Gray's * Synopsis 
of Species of American Squirrels in the Collection of the 
British Museum.'^ The latter paper recognized 18 species and 
varieties north of Panama, several of which were supposed to 
be new, and was the first formal attempt to revise the Neotrop- 
ical squirrels. Gray paid little attention to the work of pre- 
vious authors and consequently renamed a number of species. 
His descriptions were poor, the synonymy badly involved, and 
some of the species were given impossible ranges. Dr. J. 
A. Allen, in revising the group in 1877,* not only had the hope- 
less task of untangling Gray's results with the scanty material 
afforded by the museums in the United States, but was further 
handicapped by the prevailing tendency of the time to lump 
species, and as a consequence did not clear the ground. In the 
following year, 1878, Alston published a paper ' On the Squir- 
rels of the Neotropical Region,'^ based on an examination of 
series in the Berlin, Paris, and British museums, with additional 
specimens sent him by Dr. Allen. Alston states that this 
material included the types of forty-one nominal species. In 
this revision 7 species were recognized as living within the limits 

1 Charlesworth's Mag. Nat. Hist., Ill, p. 334, 1839. 

2 Sitzungsber. Akad. Wiss. Wien. math.-nat. CI., Iv, pp. 474-480. July, 1867. 
•''Ann. and Mag. Nat. Hist., 3d Ser., XX, pp. 415-434. October, 1867. 
*Mon. N. Am. Rodentia, 1877. 

sproc. Zool. Soc. London, 1878, pp. 656-670. 



20 NELSON 

of Mexico and Central America, as against 6 species and 3 
varieties enumerated by Allen. In the Mammalia of the ' Bio- 
logia Centrali-Americana,' published in 1880, Alston again 
recognized 7 species— no more than those mentioned by Lesson 
in 1842. This wholesale lumping of widely separated species — 
sometimes under a name inapplicable to any of the forms placed 
under it — left the group even more complicated than before. 

Dr. Allen followed Alston's paper of 1878 by a 'Synonymatic 
List of American Sciuri, or Arboreal Squirrels '^ in which he 
adopted the latter's conclusions. Trouessart, in his ' Revision 
du Genre Ecureuil'^ in 1880, proposed several subgenera and a 
few months later enumerated the species in his ' Catalogue des 
Mammiferes Vivants et Fossiles ' (Rodentia).^ 

During the last 18 years no extended papers on Neotropical 
squirrels have appeared, but a number of species have been de- 
scribed from Mexico and Central America by Allen, Thomas, 
Merriam and myself. 

NOTES ON DISTRIBUTION AND VARIATION. 

Tree squirrels occur in suitable places throughout Mexico 
and Central America but the distribution of the various species 
depends largely upon the character of the forests. Thus Sciurus 
negligens is most abundant in the low, dense forests of ebony, 
less than twenty-five feet high, on the hot coast plains, while 
its near relative 5. de^pei loves the shady depths of humid trop- 
ical forests on the lower mountain slopes where the damp air 
produces an exuberant tree growth and an abundance of para- 
sitic plants. The pigmy Sciurus alfari^ first mistaken by its 
discoverer for a bird — a Dendrocolaptine creeper — also lives in 
similar surroundings in the mountains of Costa Rica. The 
large species exist under even more varied conditions since 
they occur from the hot coast country to the region of oaks and 
pines close to timberline, but the ranges of different species or 
subspecies are never coincident and overlap only in a few in- 
stances, as in the case of ^S*. collicei nuchalis and S. poliopus 

iBull. U. S. Geol. & Geog. Survey Terr., IV, pp. S77-887, 1878. 
*Le Naturaliste, II, No. 37, pp. 290-293, Oct., 1880. 
3 Bull. Soc. d'Etudes Sci. d'Angers, X, pp. 76-82, 1S80. 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 21 

colimcnsis on the coast of Colima, and S. apache and S. diirangi 
in the Sierra Madre. No such antagonism exists between the 
large species (subgenus Echinoscmriis) and the smaller ones 
(subgenera Gaerlingucttis and Microscmrus) which frequently 
occupy the same ranges. 

Many species change their environment by periodical migra- 
tions in search of food, moving from one locality to another with 
the ripening of fruits or seeds upon which they subsist. This 
is most marked on high mountains where a species may have a 
vertical range of many thousand feet. Dr. Buller obtained a 
specimen of Sciiwiis poliopus cervicalis among the pines on the 
Sierra Nevada de Colima at an altitude of 12,000 feet, but when 
we visited this mountain at another season, gnawed pine cones 
were abundant near the summit, but the squirrels had de- 
scended to lower levels and were feeding on wild figs and acorns 
at an altitude of 4000-6000 feet. In eastern Queretaro and 
northern Hidalgo, S. aureogaster^ a tropical species which 
usually ranges below 4000 feet, was found in winter among the 
oaks and pines above 8000 feet alt. S. deppei likewise at 
times wanders high above its normal range. 

The effect of climate on the character of the pelage is so 
marked that it is possible to tell with considerable certainty 
whether a species belongs to the tropics or to the higher moun- 
tains. Tropical species have thin pelage, short thin under fur, 
and coarse, stiff, or almost bristly dorsal hairs ; those of the 
Transition and Boreal zones have thick soft pelage with long 
dense under fur. These differences are sometimes strikingly 
shown in subspecies of the same squirrel : thus the tropical 
Sciurtis aurcogaster hypopyrrhiis has thin coarse pelage, while 
S. aiireogaster Jrtmientor, which ranges between the altitudes 
of 6000 and 8000 feet on a cold mountain slope, has dense soft 
pelage. Species of the hot coasts of Central America are char- 
acterized by peculiarly coarse, shining, bristly dorsal hairs. 
Seasonal differences in pelage are usually slight, since there is 
no area of heavy snow fall or long continued cold weather ex- 
cept in the Sierra Madre of Durango and Chihuahua. Indi- 
vidual variation, on the other hand, is often excessive and ren- 
ders some species extremely difficult to describe. The large 



22 NELSON 

number of species and subspecies of these squirrels, together 
with their great individual variation, have hitherto proved an 
insuperable stumbling block in their treatment. The large 
series now available for study shows that the group as a whole 
is in a state of evolution and has developed groups of closely- 
related species or well marked geographic races, often within 
very limited areas. For example, in the State of Vera Cruz, 
the typical form of Sciurus aureogaster occurs throughout the 
northern part, ^5'. aureogaster frumentor on the west-central 
border, and S. aureogaster hyfopyrrhus in the southern part. 
Many of the subspecies are so different from others of the same 
species that without the intermediate series no one would for a 
moment suspect their specific identity. 

The extraordinary amount of geographical variation in trop- 
ical North American squirrels is due mainly to an unusual plas- 
ticity of organization which allows slight climatic differences to 
produce a visible effect. The most obvious of these influences 
are differences in temperature and rainfall with their distribu- 
tion through the year, and consequent effect on the vegetation. 

The cool forests of the Transition zone in the interior of 
southern Mexico and Guatemala are characterized by moderate 
rainfall and have what may be called an inland climate. The 
forests of the same zone on the mountains bordering the hot coast 
plains, exposed to the moisture bearing winds from the sea, re- 
ceive a much greater annual rainfall accompanied by cloudiness 
and mists, resulting in an exuberance of vegetation not found 
elsewhere in this zone. The effects of these differences in hu- 
midity upon the squirrels are beautifully illustrated by Sciurus 
■polio^us and its subspecies. For example, subspecies hernan- 
dezi^ nemoralis and cervicalis, of the drier interior mountains, 
are characterized by dull grayish upperparts and white under- 
parts, and the absence of sharply contrasting nape and rump 
patches. Sciurus -polio^us and its subspecies effugius inhabit 
mountains near the coast, and the effect of the increased humidr 
ity is marked by the striking contrast between their gray backs 
and bright ferruginous underparts. In addition, effugius has 
an unusually dark nape patch and brilliantly white ear patches. 

Increased humidity within the tropics, also, is usually accom- 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 23 

panied by increased intensity of coloration. This is well shown 
by the dark, rich colors of Sciurus aureogaster hyfofyrrhus of 
the humid tropics compared with the paler colors of the closely 
related S. aureogaster^ of the arid tropics a little farther north. 
A similar intensification of color is characteristic of the squir- 
rels inhabiting the humid east coast from Vera Cruz to Pan- 
ama, as contrasted with the paler species of the more arid west 
coast from Mazatlan to Costa Rica. 



SUBGENERA OF NORTH AMERICAN SQUIRRELS. 

The tree squirrels of North America may be separated into ten 
groups, distinguished by cranial, and sometimes by external 
characters. Six of these groups have been already recognized 
as of subgeneric rank, and four others are here named. 

In discriminating the subgenera of squirrels one of the charac- 
ters on which much stress has been laid is the presence or absence 
of the small upper premolar. The discussion of the groups in 
detail is prefaced, therefore, with a few remarks on this tooth. 
Trouessart makes the erroneous statement that in the subgenus 
Macroxus the upper molar series is often | in the young and | 
in the adult, adding that the rudimentary premolar is more or 
less speedily shed.^ Under Macroxus he names six Tropical 
American squirrels, viz., aureogaster, cestuans, hoffmanni\ 
deppet, chrysurus, and pusillus. Of these mstuans and hoff- 
manni never have the extra premolar, while all of the others, 
with the possible exception of chrysurus, always have it in the 
adult skull. The six species named above represent four sub- 
genera, two of which were recognized by Trouessart in the same 
paper ; one has since been separated by Allen ; another is de- 
scribed below. In all North American Squirrels having the extra 
premolar, except the Chickarees or Red Squirrels of the United 
States and Canada (subgenus Tamiasciurus), it is well devel- 
oped and permanent. Among the Chickarees it is extremely 
small, variable in size, shape, and position, and frequently ab- 
sent. Dr. Allen states, in his recent revision, that it is absent 

'Le Naturaliste, II, No. 37, pp. 292, Oct., 1S80. 



24 NELSON 

in thirty percent of the specimens examined. In the skulls of 
Tamiasciiirus examined by me the percentage of absences is 
much smaller than that given by Dr. Allen, but the tooth was fre- 
quently so minute that it could be seen only by the aid of a lens. 
It is smallest, most variable and most frequently absent in the 
eastern S. htidsoniciis and its subspecies. In the other groups 
of North American squirrels, this tooth, when present, is a well- 
developed peg, reaching nearly or quite as high as the 2d pre- 
molar, and often functional, the crown wearing down with the 
adjacent teeth. Skulls from Mexico show conclusively that in 
the species of that region, at least, the small premolar is a char- 
acter of the adult. It is not present with the milk premolar in 
immature skulls, but appears coincidently with the permanent 
premolar and is equally persistent. Since it is persistent in cer- 
tain groups and always absent in others, it evidently possesses 
considerable taxonomic value. 

The subgenera recognized in the present paper occupy 
clearly defined geographic areas and, without exception, the 
ranges of the most closely related groups are separated by 
a distinct gap. A curious equality is found in the number of 
subgenera belonging respectively to Tropical and Temperate 
North America. Five of the ten subgenera belong essentially to 
Mexico and Central America, only one having a representative 
within the United States. The remaining five belong to Tem- 
perate North America, although four of them have each a single 
representative in extreme northern Mexico. The distribution of 
the subgenera may be tabulated roughly as follows : 

MEXICO AND CENTRAL AMERICA. UNITED STATES. 

Baiosciurus subgen. nov. Tamiasciiirus Trouess. 

EcJiinosciurus Trouess. JSfeosciurus Trouess. 

ArcEosciurus subgen. nov. Parasciurus Trouess. 

Not represented. Otosciurus subgen. nov. 

Not represented. Hesperosciurus subgen. nov. 

Giierlingtietus Gray. Not represented. 

Microsciurus Allen. Not represented. 

The extra premolar is present in all of these groups except 
ArcBoscitirus, Parasciurus, and Guerlingiietus. Gucrlinguetiis 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 25 

and 3Iic)'osciufiis are South American groups with numerous 
species, and occur as intrusive elements in Central America, 
where each is represented by one or two species. Otosciurus 
and Hester oschir lis have few species and belong to the western 
United States, but cross the border into Mexico. 

The first name available for a subgenus of American Squirrels 
is Gtterlingiietus Gray, 182 1, of which Macroxush a synonym. 
Macroxtis, the name which has been commonly used, has been 
curiously diverted from its original application to include nearly 
all American squirrels. Lesson was the first to misuse the name, 
after which Gray went to even greater extremes, in which he was, 
to a certain extent, followed by Trouessart in 1897. In 1880 the 
last named author estabhshed several subgenera of American 
squirrels, several of which were accepted by Merriam and 
Allen ; yet in 1897 he again lumped several of them in the 
ancient confusion under Macroxus. The most recently described 
subgenus is Microscmrus Allen, 1895. 

LIST OF SUBGENERA WITH TYPE SPECIES. 

Echinoscmrus^ type 5. hypopy rr hus W^-glcr (p. 25, 38). 
Hesperosciurus^ type S. griseus Ord (p. 27, S3). 
JVeoscitirus^^ type >5. caroUnensis Gmelin (p. 27). 
Otosciurus^ type S. a^^r// Woodhouse (p. 28, 85). 
Tatniasciurus^ type S. hudsonicus Erxleben (p. 28, 87). 
Arccoscmrus^ type 6". oculatus Peters (p. 29, '^'$)). 
Parasciurus, type S. 7iiger Linnaeus (p. 30, 97). 
Gzierlinguetus^ type S. gtcei-linguet?is Gv^y (p. 30, 98). 
Baiosciuriis, type S. deppeil^Qtexs (p. 31, loi). 
Aficroscitirus, type S. alfar i AWen (p. 32, 105). 

Subgenus ECHINOSCIURUS Trouessart (p1. I, fig. 9). 

Echinosciurus Trouessart, Le Naturaliste, II, No. 37, Oct. 18S0, p. 

292; Cat. Mamm., Rodentia, pp. 80-81, 1880 (part). 
J/a<:ro.Y«5 Trouessart, Catalogus Mammalium, nov. ed., II, pp. 421- 

429, 1897 (part). . ^^ • 

Type Sciurus hypopyrrhus Wagler, from Mexico. 

^Neosciuyus is included here in order to complete the revision of the sub- 
genera of North American squirrels. 



26 NELSON 

Distribution. — All of Central America and Mexico (except extreme 
northern part). Ranges from Arid and Humid Tropical zones up to 
Boreal. 

External characters. — Form and color extremely variable : body 
usually rather slender ; tail long, narrow ; pelage coarse, stiff, almost 
bristly, in typical species. 

Cranial characters. — Premolars \. Skull short, broad, depressed ; 
brain case not highly arched but expanded laterally and widening to 
occiput; interorbital area broad, rostrum short, broad, and heavy; 
nasals about equal to or shorter than interorbital width. 

Ge?ieral notes. — S. hypopyrrhus Wagler was named as the type 
of Echinosciuriis.1 but most of the red bellied Central American 
squirrels were given that name at the time Trouessart wrote, and he 
no doubt had in mind some bristly haired species from Central Amer- 
ica instead of Wagler's animal. However, Wagler's hypopyrrhus 
belongs to the same natural group and must therefore be retained as 
the type. Most of the large squirrels in tropical North America belong 
to this group. The skulls are distinguished from those of other large 
North American species by the combination of two upper premolars 
with a short broad rostrum and flattened interorbital region. Echino- 
sciurus contains 6". aureogaster., S. poliopus^ S. yucatanensis^ S. 
colliceif S. truei., S. sinaloensis^ S. nelsoni^ S. socialis., S. griseo- 
Jlavus^ S. goldmani^ S. nianaguensis., S. boothice^ S. adolphei and 
S. thomasi with their subspecies. These species occupy nearly all of 
the hot coast region of tropical North America and range thence over 
the mountains of Central America and southern Mexico. Those of 
the highlands of Guatemala and southern Mexico are distinguishable 
from those of the hot coasts and the interior of Central America by their 
much longer and softer pelage. In the former series are S. aureogaster^ 
S. poliopus, S. truei.1 S. sinaloensis and S. griseojiavus^ with their 
subspecies. The species of the hot districts on the coast and south- 
ward are remarkable for the stiff, harsh and usually shining long hairs 
of the back — the character upon which the name of the subgenus 
must have been based. S. yucatanensis with white ear tufts, and S. 
poliopus with a comparatively long, slender rostrum and soft pelage 
are least typical. 6*. aureogaster hypopyrrhus, the type, is about 
midway, in the character of its pelage, between the soft haired species 
of the highlands and the harsh haired species of Central America. 
The wide geographic range and large number of species of this 
group are accompanied by a greater amount of specific variation in the 
skull than is shown in the smaller groups. In the species of Central 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 27 

America there seems to be a curious correlation between the increased 
thickness of the rostrum and the increased coarseness of the pelage, 
the extreme of which is reached in S. t}io7nasi. 

HESPEROSCIURUS^ subgen. nov. (p1. I, fig. 5). 

Type Sciiirus griseus Ord, from the Dalles of the Columbia. 

Distribution. — Extreme southwestern Washington, western Ore- 
gon, and most of California, to northern Lower California, Mexico. 
Transition zone and border of Upper Sonoran. 

External characters. — Size very large — total length about 560 mm. ; 
tail a little shorter than head and body, very broad and bushy. 

Cranial characters. — Premolars f ; molar series, including small 
premolar, unusually heavy ; skull large and long, with long and deep 
rostrum ; nasals long, expanded anteriorly and much narrowed poste- 
riorly ; brain case depressed and broadened across parietal region ; pos- 
torbital process of malar strongly developed and usually ending in a 
point. Skull most like that of Neosciurns, especially in proportions 
of rostrum and interorbital area, but decidedly more depressed and 
broadened posteriorly ; the zygomatic process of squamosal thrown out 
horizontally, and the zygomatic arch inclined less obliquely upward. 
General notes. — Hesperosciurus is a small group containing only S. 
griseus Ord and its subspecies nigripes Bryant. It is limited to the 
Transition and upper part of Upper Sonoran zones of the Pacific Coast 
States and has its nearest relative in the Gray Squirrels {Neoscizcrtis) 
of the eastern United States. Like the latter the color is uniform 
gray above and white below, the group distinctions resting mainly on 
cranial characters. 

Subgenus NEOSCIURUS Trouessart. 

Neosciurtis Trouessart, Le Naturaliste, II, No. 37, Oct. 1880, p. 

292; Cat. Mamm., Rodentia, pp. 76-77, 1880 (part); Merriam, 

Proc. Biol. Soc. Washington, VII, p. 27, 1892 (part). 
J/a<:ro.v;/5 Trouessart, Catalogus Mammalium, nov. ed., II, p. 421, 

1897 (part). 

Type Sciurus carolinensis Gmelin, from Carohna. 

Distribution.— Y.A^iern half of United States, not reaching Mexican 
border. Lower and Upper Austral and Transition zones. 

External characters.— Form rather slender; tail bushy; upper- 
parts gray or grayish brown; underparts white. Externally much 
like certain species of Ara:osciurus but with different tooth formula. 

1 From ea-ivepog, western ; -f Sciurus. 



28 NELSON 

Crafzial characters. — Premolars |-. Skull long and rather narrow ; 
braincase inflated over interparietal region ; rostrum long, compressed 
laterally ; nasals much longer than interorbital breadth, much narrowed 
posteriorly and expanded anteriorly ; occiput high and narrow ; 
squamosal process of zygomatic arch turning abruptly down, the arch 
ascending more obliquely from back to front than m Hesperosciurus. 

General notes. — This subgenus includes S. carolinensis and its 
subspecies of the eastern United States. It is an Austral and Tran- 
sition zone group. Neosciurus is most closely related to Hespero- 
sciurus^ from which it is distinguished by the braincase, which is 
highly arched over the interparietals and narrowed and rounded pos- 
teriorly. These two groups balance one another in the eastern and 
western United States much as do Parasciurus and Arccosciiirus. 

OTOSCIURUS^ subgen. nov. (p1. I, fig. 3). 

Type Sciurus a^^?/-// Woodhouse, from San Francisco Mt., Arizona. 

Distribution. — Rocky Mountains and Sierra Madre, from state of 
Colorado to Durango, Mexico. Transition zone. 

External characters. — Ears long and broad, with magnificent 
tufts in winter ; tail short and unusually broad ; feet very large. 
Upperparts mainly gray ; underparts white, with lateral line more or 
less distinctly black. 

Cranial characters. — Premolars -f. Skull short and broad; frontal 
area flattened; braincase depressed, inflated laterally; rostrum com- 
pressed laterally, rather light ; nasals long (equalling interorbital 
breadth) . 

General notes. — Otosciurtis like Tamiasciurus has strong ex- 
ternal characters by which it may be at once recognized. The group 
contains three species, S. aberti., S. concolor, and S. durangi., which 
range through the yellow pine forests of the Transition zone in the 
southern Rocky Mountains and northern Sierra Madre. 

Subgenus TAMIASCIURUS Trouessart (p1. I, fig. 8). 

TamiasciurusT'RO\5'E.'S,SP<B.T ., Le Naturaliste, II, No. 37, Oct. 18S0, p. 

292; Cat. Mamm., Rodentia, pp. 81-82, 1880; Merriam, Proc. 

Biol. Soc. Washington, VII, p. 23, 1897; Allen, Bull, Am. Mus. 

Nat.'Hist., N. Y., X, pp. 249-398, 1898. 
Macroxus Trouessart, Catalogus Mammalium, nov. ed., II, pp. 421- 

429, 1897 (part). 
Type ''Sciurus hudsonius Pall.' (= 6". htidsonicus Ei"xl.), from 
Hudson Bay. 

^ From oyf, dir-of, ear ; + Sciurus. 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 29 

Distribtdion. — Most of the wooded parts of the United States and 
British America ; south to northern Lower California, Mexico. Bo- 
real and Transition zones. 

External characters. — Size small — under 450 mm. ; ears long, 
well haired, conspicuously tufted in winter; tail short, bushy, flat- 
tened ; lateral line (present in summer) black. 

Cranial characters. — Premolars | sometimes \ (the first very small 
and irregular in development) ; skull short, wide and depressed ; ros- 
trum short and stout ; nasals shorter than interorbital breadth ; anterior 
end of zygomatic arch unusually broad and abruptly spreading ; aud- 
ital bullae proportionately large. 

General notes. — Tainiaschirus was proposed by Trouessart in 1880 
and subsequently dropped into synonymy until revived by Dr. Mer- 
riam in 1892. Curiously enough Trouessart reduced it again to 
synonymy in 1897, uniting it with most other North American squir- 
rels under the untenable subgeneric name Macroxus. In 1898 Dr. 
Allen again revived the subgenus, which is unquestionably worthy of 
recognition as a well marked natural group. Tamiasciurus includes 
all of the Chickarees, S. hudsonicus, S. douglasi and S. fretnonti 
with their subspecies. As already stated by Dr. Merriam, this sub- 
genus is of Boreal origin, but is also common throughout a large part 
of the Transition zone in the United States. 

AIL^OSCIURUS ^ subgen. nov. (p1. I, fig. 3). 

Type Sciurus oculatiis Peters, from eastern Mexico. 

Distribution. — Mountains bordering the tableland of Mexico from 
the volcanoes of Orizaba and Toluca north to central Arizona and 
west-central New Mexico. Transition zone. 

External characters.— '^\-lq\2^x^Q\ body rather slender; tail usually 
long, sometimes exceeding length of head and body ; upperparts gray 
or yellowish ; underparts white or yellowish. 

Cranial characters.— Yx^moXax^ \. Skull rather short, depressed ; 
braincase broadened at parietals ; occiput low and broad ; front of 
skull depressed at base of rostrum (more arched in Parasciurus) ; ros- 
trum light ; nasals narrow, slightly tapering posteriorly ; upper end of 
premaxillte narrow. 

General notes— ThQ subgenus Arceosciurus is characteristic of the 
Transition zone in the mountains bordering the tableland of Mexico 
from Mts. Orizaba and Toluca northward. It is intrusive in the United 

1 From apaloq, slender ; + Scitirus. 



30 NELSON 

States, where it is represented in Arizona and western New Mexico by 
a single species, S. arizo7iensis. The group is most nearly related to 
Parasciurus from which the skull characters distinguish it. The fol- 
lowing species and subspecies belonging to this subgenus : S. oculatus^ 
S. o. tolucce^ S. alleni^ S. nayaritensis^ S. apache^ S. arizonensis 
and S. a. huacJmca. 

Subgenus PARASCIURUS Trouessart (p1. I, fig. i). 

Parasciurus Trouessart, Le Naturaliste, II, No. 37, Oct. 1880, p. 

292; Cat. Mamm., Rodentia, pp. 77-78, 1880 (part); Merriam, 

Proc. Biol. Soc. Washington, VII, p. 27, 1892. 
Macroxus Trouessart, Catalogus Mammalium, nov. ed., II, p. 421, 

1897 (part). _ 
Type Sciuriis niger Linn., from Carolina. 

Distribution. — Eastern half of United States, entering Mexico 
from western Texas. Upper and Lower Austral (Sonoran) zones. 

External characters. — Size large; body slender; tail long, rather 
bushy. Upperparts grizzled blackish or yellowish ; underparts black- 
ish or yellowish. 

Cranial characters. — Premolars \. Skull rather long, rostrum 
long and broad, nasals broad ; braincase long, narrow, not inflated 
over parietals and narrowed at occiput. 

General notes. — The subgenus Parasciurus is limited to the Fox 
Squirrels, S. niger and S. ludovicianus with their subspecies. It is 
distinguished from Arceosciurus mainly by the long narrow braincase 
and heavier rostrum. The ranges of the two groups do not touch at 
any point. 

Subgenus GUERLINGUETUS Gray (p1. I, fig. 7). 

Guerli7tguetus Gray, London Medical Repository, XV, p. 304, 

April, 1821. 
Macroxus F. Cuvier, Dents des Mamm., p. 162, 1823. (Type, le 

guerlinguet) ; Diet. Class. d'Hist. Nat. X, p. 16, 1826; Lesson, 

Nouv.Tabl. Regn. Anim., Mamm., p. 11 1,1842 (part) ; Gray, Ann. 

& Mag. Nat. Hist., 3d Ser., XX, pp. 271, 419-434, 1867 (part) ; 

Trouessart, Le Naturaliste, II, No. 37, 18S0, p. 292 (part) ; Cat. 

Mamm., Rodentia, pp. 78-80, 1880 (part) ; Catalogus Mammalium, 

nov. ed., II, pp. 421-429, 1897 (part). 
Type., 'le guerlinguet' — 6". gzierlingjietus Gray (^ Sciurus ces- 

tuans Linn.), from Surinam. 

Distribution. — Tropical America from Peru and Brazil to Nica- 
ragua. 

External characters. — Size rather small — total length between 300 
and 450 mm. ; ears long, thinly haired; tail shorter than body, rather 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 3 1 

bushy, flattened; color usually some shade of brown on upperparts 
and buffy or rufous below. 

Cranial characters. — Premolars \. Skull rather broad, flattened 
interorbitally ; rostrum broad and deep at base ; nasals long, ex- 
panded at outer end ; braincase not very highly arched but expanded 
laterally over parietal region ; audital bullce small ; post-palatal notch 
a little farther behind last molar than in Microscuirus (about as in 
Baiosciurus^ ; palatal width between molar series great. The skull 
resembles in size and general appearance that of Baioscittrus^ from 
which it is distinguishable by slender rostrum, proportionately greater 
interorbital and zygomatic breadth, and by the absence of the small 
premolar. 

General notes. — Guerlinguetus., proposed by Gray in 182 1, is the 
first name available for a subgenus of American squirrels. It was 
subsequently discarded by its author for Alacroxus., proposed two 
years later by Cuvier in the ' Dents des Mammiferes.' In the ' Nom- 
enclator Zoologicus,' Agassiz cites Macroxus from the ' Dictionnaire 
des Sciences Naturelles, X, 1S18,' but a careful search fails to verify 
the reference. The name does appear in the Dictionnaire Classique 
d'HistoireNaturelle, Vol. X, 1S26, p. 16, which was probably the cita- 
tion intended by Agassiz. The ' Dents des Mammiferes' was completed 
in 1825, but on page xvi of the introduction Cuvier states that the 
work appeared in parts, and that the part containing the rodents was 
issued in 1S23 ; from which therefore must date Macroxus. Subse- 
quent writers have followed Gray in ignoring Guerlinguetus in favor 
of Macroxus. The latter name was proposed for the group typified 
by Sciurus cestuans of South America, yet Lesson in 1S42, Gray 
in 1S67, and Trouessart in 1880 and 1897, included under it the 
most diverse squirrels in America. Guerlinguetus should be strictly 
limited to 6". cestuans with its numerous subspecies and allies, all of 
which have brownish backs with brown, fulvous, or rufous bellies and 
a single upper premolar. It is a characteristic group of northern 
South America, intrusive in Central America where it is represented 
by S. a. hofftnanni of Costa Rica and S. richmondi of Nicaragua. 

BAIOSCIURUS^ subgen. nov. (p1. I, fig. 4.) 

Type Sciurus deppei Peters, from Papantla, Vera Cruz. 

Distribution. — Northeastern Honduras, Guatemala, Chiapas and 
eastern Mexico to Tamaulipas. 

^ From [iai6r, small ; + Scinrus. 
Proc. Wash. Acad. Sci., May, 1899. 



32 NELSON 

Extertial cha7'actcrs. — Size small — total length between 350 and 
400 mm.; ears long, thinly haired; tail slightly shorter than body, 
narrow and flattened. 

Crafzial characters. — Premolars |^, well developed ; skull rather 
long and slender; rostrum broad and deep at base; nasals about equal 
to interorbital breadth ; anterior end of zygomatic arch narrow and 
tapering gradually to junction with premaxilla ; braincase rounded 
and slightly arched on posterior half of frontals ; audital bullae propor- 
tionately small, smaller than in Guerlingiietus and much smaller 
than in Tarniasciurus . 

General notes. — Baiosciurus contains but two species, S. deppei 
and S. neglige7is. In size and general style of color these squirrels 
are very similar to members of the subgenus Guerlingiietus., but are 
distinguished by the presence of an extra premolar and other skull 
characters. Their size, shape of tail, and form of skull distinguish 
them from Microsciurus ; and the slender tail, presence of a w^ell de- 
developed small premolar, lack of ear tufts, absence of the black 
lateral line and shape of skull separates them from Tafniasciurus. 
The group is purely tropical, S. deppei belonging to the Humid and 
S. negligens to the Arid Tropical zones. 

Subgenus MICROSCIURUS Allen (p1. I, fig. 6). 

Microsciurus Allen, Bull. Am. Mus. Nat, Hist., VII, p. 333, 1895 '■> 

Trouessart, Catalogus Mammalium, nov. ed., II, p. 429, 1897. 
Type Sciurus alfari Allen, from Jimenez, Costa Rica. 

Distributio7i — Northern South America north to Costa Rica, Cen- 
tral America. 

Extertial characters — Smallest of American squirrels — total length, 
in nearly or quite all the species, under 300 mm. Ears short, rounded, 
well haired; tail much shorter than body, slender and rounded. 

Cranial characters — Premolars y. Skull short, broad and highly 
arched over braincase : rostrum short, broad and deep at base ; nasals 
narrow^ and shorter than interorbital breadth ; upper end of premax- 
illae very heavy; malar broad and expanded vertically; postpalatal 
notch only a trifle posterior to last molar. 

General notes. — Microsciurus is a tropical American subgenus 
with numerous species distributed over a large part of northern South 
America and may be considered intrusive in Central America, S. al- 
fari being the only species known north of Panama. S. pusillus 
Desm., S. kuhli (Gray), 6". peruatius KW^w., S. 7ni?nulus Thomas, 
and other South American species belong here. Until Dr. Allen de- 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 33 

fined this group its members were confused with the species of the 
subgenus Guerlinguetus Gray {Macroxtis Cuvier) which are charac- 
terized by a single upper premolar. 

KEY TO SPECIES AND SUBSPECIES. 

Size large, total length over 450 mm. 
Premolars -i- 

Belly bu^y or yellowish 
Back gray 

Median area on back black ; belly usually deep buff 

oculatus p. 88. 
Median area on back washed with blackish ; belly 

buffy whitish tolucce p. 89. 

Back yellowish gray 

Belly rusty yellow; total length over 500 mm. 

apache p. 94. 
Belly more dingy yellow; total length under 500 

mm liTnitis p. 97. 

Belly white 

Back golden buffy or yellowish overlaid with grizzling 

of black and white nayaritefisis p. 93. 

Back gray 

Back uniform gray or grayish brown ; ears gray ; 

total length under 500 mm alleni ■^. 91. 

Back gray washed with yellowish on nape and 
back of shoulders; ears rusty ; total length over 

500 mm huachuca ^. 96. 

Premolars f 

Nape patch strongly marked, rump patch present or absent 

Belly gray ^ luhite, or buffy 

Belly gray, rump patch well marked; back dark 

gray Jrumentor p. 44. 

Belly white or buffy 

Rump patch poorly defined or absent 

Back dull whitish ; belly white or buffy 

social is p. 63. 
Back pale gray ; belly white or buffy 

hernandezi p. 48. 
Rump patch well defined 

Middle of back gray ; feet gray or black- 
ish ; belly white colimefisis p. 52. 

Middle of back whitish ; feet whitish, belly 

white or buffy cocos p. 65. 

Belly rufous 

Feet gray or blackish 

Ribs and sometimes shoulders rufous 

Back pale gray ; top of head iron gray 

aureogaster p. 38. 



34 NELSON 

Back dark gray ; top of head iron gray or 

blackish hypopyrrhus p. 42. 

Ribs and shoulders not rufous 

Back dingy whitish ; nape patch rusty 

social is p. 62. 
Back bluish gray in middle, remainder 

sooty brownish hirtus p. 56. 

Feet white 

Back whitish, rump and nape patches very 

bright cocos p. 65. 

'* Back gray 

Nape patch strongly marked, dark rufous 

effugius p. 54. 
Nape patch not strongly marked, rusty 

yellowish poliopus p. 46. 

Nape and rump patches absent or not well defined 
Nape and rump patches not well defined 

Back dark gray, sparingly or not at all mixed with yellowish hairs 
Back and under side of tail dark iron gray ; feet gray 

cervicalis p 51. 
Back and under side of tail paler gray ; feet white 

nemoralis p. 50. 
Back pale gray mixed with yellowish hairs ; feet white 

Belly white hernandezi p. 48. 

Belly rufous , .poliopus p. 46. 

Nape and rump patches absent 

Back with broad median band of blackish ; rest of body whitish 

dorsalis p. 74« 
Back without broad median band of blackish 

Belly pale gray ; back coarsely grizzled gray or yellowish gray 

yiicatanensis p. 70. 
Belly not pale gray 
Belly blackish or white 

Belly blackish ; back sooty blackish grizzled with yellow- 
ish gray , nelsoni p. 55. 

Belly white 

Ear tufts present, whitish ; back gray or yellowish gray 

yucatanensis p. 70. 
Ear tufts absent 

Ears bordered ivith black 

Back very dark, lateral line reddish ; ear patches 

rusty boothice p. 76. 

Back grayer, no lateral line ; ear patches very large, 

white .goldinani p. 82. 

Ears not bordered %vith black 

Back pale gray or yellowish, Jinely grizzled with 

black 
Back gray 

Size large; total length about 570 mm.; back 
vmiform ; no lateral line .griseus"^. 83. 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 35 

Size medium, total length about 485 mm. ; me- 
dian dorsal area rufous ; lateral line black 

durangi p. 85. 
Back yellowish 

Ears pale rusty; flanks like back.../r«c/p. 61. 
Ears dull rusty ; flanks washed with whitish 

sinaloensis p. 60. 

Back yellowish gray, coarsely grizzled with black 

Ears gray; yellowish of back dull, sometimes 

very indistinct collicei p. 58. 

Ears rusty; yellow of back brighter, more buffy. 

nuchalis p. 59. 
Belly not blackish or white 
Belly buffy 

Back with median area blackish or dark brown, rest of 

body buffy dorsalis p. 74. 

Back with median area not blackish 

Ears black edged variegatoides p. 79. 

Ears not black edged ftiaftaguensis i>. 81. 

Belly rufous 

Top of head paler than back 

AH of back blackish brown ; feet, legs, lower flanks 

and belly dull chestnut rufous adolphei ^. 73. 

Middle of back blackish or dark yellowish brown 
or grayish yellow ; rest of body rufous 

dorsalis p. 74. 
Top of head not paler than back 
Back heavily washed with black 

Belly rusty I'ufous belti ^. 78. 

Belly rich dark ferruginous tkomast "p. 71. 

Back not washed with black 

Sack pale gray or sooty blackish 
Back pale gray 

Feet dark gray or blackish ; rufous of belly 
sometimes extending up on ribs 

aureogaster p. 38. 
Feet pale gray ; rufous of belly not extending 

up on ribs chiapensis p. 69. 

Back sooty blackish, with thin wash of yellowish 

gray 

Back uniform nelsoni p. '^$. 

Back with area of bluish gray across the mid- 
dle hirtus p. 56. 

Back not pale gray or sooty blackish 

Back yellowish brown sometimes thinly washed 

with gray .griseojlavus 1^. 67. 

Back blackish, grizzled with gray or yellowish ; 
underparts and costal area rufous 

hypopyrrhus p. 42. 



36 NELSON 

Size small, total length under 450 mm. ; premolars y or f 
Premolars i; ears medium long, thinly haired (Subgenus Guer- 
linguetus) 

Tail washed with bright ferruginous hoffmanni p. 98. 

Tail washed with yellowish rickmondi -p. 100. 

Premolars f 

Ears large, tufted (Subgenus 7 amiasciurus) 

Back gray, belly white, lateral line hXdiQ^^.mearnsi p. 87. 
Ears small or medium, not tufted 

Ears short, rounded, thickly haired ; total length under 
300 mm. (Subgenus Microsciurus') 

Tail washed with reddish alfari p. 105. 

Ears medium long, pointed, thinly haired; tail washed 
with white ; total length over 300 mm. (Subgenus 
Saiosciurtis) 

Back grayish brown negligens p. 1 04. 

Back reddish or yellowish brown deppei ^. loi. 



LIST OF SPECIES, TYPE LOCALITIES, AND SPECIMENS 
EXAMINED. 



Name. 



Sciurus aureogastet F. Cuv. 

hypopyrrhiis 

(Wagl.) 
frumentor Nelson 
foliofus (Fitzinger) 

hernandezi Nelson 

nemoralis Nelson 
cervicalis (Allen) 
colimensis Nelson 
effugius Nelson 

nelso7ii Merriam 

hirtus Nelson 
collicei Richardson 

nuchalis sub sp. nov 
sinaloensis sp. nov. 
iriiei sp. nov. 
socialis Wagner 

cocos Nelson 
griseoflavus (Gray) 

chiapensis subsp. n 



Type Locality. 



Eastern Mexico [Typical at AltaMira, 

Tamaulipas] 
' Mexico' [Typical at Minatitlan, 

Vera Cruz] 
Las Vigas, Vera Cruz, Mexico 
' Cordillera of Oaxaca' [Typical on 

Cerro San Felipe] Oaxaca 
Mts. w. of Oaxaca City, Oaxaca, 

Mexico 

Patzcuaro, Michoacan, Mexico 
Sierra Nevada de Colima, Jalisco, Mex. 
Hacienda Magdalena, Colima, Mexico 
Mts. w. of Chilpancingo, Guerrero, 

Mex. 
Huitzilac, Morelos, Mexico 
Tochimilco, Puebla, Mexico 
San Bias, Tepic, Mexico 
Manzanillo, Colima, Mexico 
Mazatlan, Slnaloa, Mexico 
Camoa, Rio Mayo, Sonera, Mexico 
Near Tehuantepec City, Oaxaca, Mex 
Acapulco, Guerrero, Mexico 
' Guatemala ' [Typical near Duenas] 
San Cristobal, Chiapas, Mexico 



No. of 
specimens 
examined. 



16 

17 

32 
24 
10 



18 

7 
24 
17 

4 

4 

54 

33 

22 
12 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 



37 



LIST OF SPECIES, TYPE LOCALITIES, AND SPECIMENS 
EXAMINED. 

( Continued. ) 



Name. 


Type Locality. 


No. of 
specimens 
examined. 


yucatanensis Allen 


Merida, Yucatan, Mexico 


5 


t/iomasi sp. nov. 


Talamanca, Costa Rica 


5 


adolphei (Lesson) 


Realejo, Nicaragua 


I 


dor salts (Gray) 


\V. coast Central America [Typical at 






Liberia, Costa Rica] 


20 


boothtcB Gray 


' Honduras' [Typical at San Pedro 






Sula] 


8 


Sc turns booth i(e belli subsp. 






nov. 


Escondido River, Nicaragua 


8 


variegatoides Ogilby 


Salvador, Central America 


I 


managuensis Nelson 


Managua River, Guatemala 


3 


goldmani Nelson 


Huehuetan, Chiapas, Mexico 


lo 


griseus Ord 


The Dalles of the Columbia, Oregon 




durangi (Thomas) 


Ciudad Ranch, Durango, Mexico 


52 

32 


douglasi mearnsi 


San Pedro Martir Mts., Lower Cali- 




(Town.) 


fornia, Mexico 


3 


oculatus Peters 


Eastern Mexico [Typical at Las Vigas, 






Vera Cruz] 


46 


toluccE Nelson 


Volcano of Toluca, Mexico 


15 


allcni Nelson 


Monterey, Nuevo Leon, Mexico 


22 


nayaritensis Allen 


Valparaiso Mts., Zacatecas 


41 


apache Allen 


Near Bavispe River, Chihuahua, Mex. 


33 


arizonensis huachuca 






Allen 


Huachuca INIts., Arizona 


26 


ludovicianus limitis 






(Baird) 


Devil's River, Texas 


H 


cestuans Jtoffmatini Peters 


Costa Rica [Typical near San Jose] 


25 


richtnondi Nelson 


Escondido River, Nicaragua 


18 


deppei Peters 


Papantla, Vera Cruz, Mexico 


73 


negligens Nelson 


Alta Mira, Tamaulipas, Mexico 


23 


alfari Allen 


Jimenez, Costa Rica 


3 



38 NELSON 

SYSTEMATIC DESCRIPTIONS OF SPECIES.' 
Subgenus ECHINOSCIURUS Trouessart. (p1. I, fig. 9.) 
SCIURUS AUREOGASTER F. Cuvier. Red-bellied Squirrel. 

Sciurus «/f^r Erxleben, Syst. Regni Anim., pp. 417-418, 1777 (part: the 
melanistic form — Sciurus 7nexicanus or Quautechallotlthliltic of Hernan- 
dez, p. 582. Not S. niger Linn., 1758.) 

Sciurus variegatus Desmarest, Nouv. Diet. d'Hist. Nat., x, pp. 103-104, 1817 
(part); Saussure, Revue et Mag. de Zool., pp. 4, 5, 1861 ; Alston, 
Proc. Zool. Soc. London, pp. 660-662, 1878 (part) ; Biol. Cent. -Am., 
Mamm., pp. 127-128, 1880 (part: specimens from Orizaba, Cordova, 
Mirador, Santuario and Jalapa, Vera Cruz) ; Sumichrast, La Naturaleza, 
V, p. 324, 1882 (part : specimens from central Vera Cruz) ; Thomas, Proc. 
Zool. Soc. London, p. 74, 1890, (Not S. variegatus Erxleben 1777.) 

Sciurus aureogaster F. Cuvier, Hist. Nat. Mammiferes, vi, livr. Lix, pi. with 
text, 1829; Bachman, Proc. Zool. Soc. London, pp. 88-89, 1838; I. 
Geoffroy, Voyage de la Venus, Zool., Atlas, pi. 11, 1846 ; text, pp. 156- 
163, 1855 (part : specimens described with rufous lower surface) ; Baird, 
Mamm. N. Am., p. 282, 1857; Allen, Bull. Am. Mus. Nat. Hist., N. 
Y., Ill, pp. 181-182, 1890 (part: specimens from Tampico) ; Ibid., iii, 
p. 222, 1 891 (part : specimens from Valles, San Luis Potosi, and Tampico, 
Tamaulipas. 

Sciurus rafiventer Lichtenstein, Abhandl. K. Akad. Wiss. Berlin, p. 116 
(1827), 1830. 

Sciurus leucogaster Y . Cuvier, Suppl. d'Hist. Nat. Buffon, I, pp. 300-301, 

1831. 
Sciurus mustelinus Audubon and Bachman, Proc. Acad. Nat. Sci. Phila., 

pp. loo-ioi, 1841 (melanistic) ; Journ. Acad. Nat. Sci. Phila., viil, pt. 2, 

p. 312, 1842 ; Quad. N. Am., iii, pp. 258-259, pi. CLii, 1851. '" 

Sciurus ferruginiveiiiris Audubon and Bachman, Proc. Acad. Nat. Sci. 

Phila., p. loi, 1841 ; Journ. Acad. Nat. Sci. Phila., viii, pt. 2, p. 313, 

1842 ; Quad. N. Am., I, pp. 292-293, pi. xxxviii, 185 i. 
Sciurus ferrugineiventr is Schinz, Synopsis Mamm., 11, p. 14, 1845. 
Sciurus aurogasiar AvDVBO^ and Bachman, Quad. N. Am., ill, p. 344, 1851. 
Sciurus hypoxanthus (Lichtenstein MS) I. Geoffroy, Voyage de la Venus, 

Zool. (text), pp. 158-159, 1855 (on labels of squirrels from BerHn Museum). 
Sciurtis chrysogaster Q\YJe>^\., Saugethiere, p. 650 footnote, 1855. 
Macroxus aureogaster Gray, Ann. and Mag. Nat. Hist., 3d ser., xx, 423, 

1867 (var. 2 from Mexico). 
Sciurus aiireigaster KxAJE.^, Mon. N. Am. Rodentia, pp. 75f>-753. ^"^11 (part: 

specimens from Orizaba, Cordova, and Mirador, Vera Cruz); Bull. U. S. 

Geol. Survey Terr., iv, pp. 882-883, 1878. 
Sciurus hypopyrrhus Allen, Bull. Am. Mus. Nat. Hist., N. Y., iii, pp. 

222-223, 1891. (Melanistic specimens from Tampico, Mexico.) 
Sciurus leucops Allen, Bull. Am Mus. Nat. Hist., N. Y., ix, p. 198, 1897. 

Type locality. — ' California ' — really eastern Mexico. Specimens 
from Alta Mira, Tamaulipas are typical. Type in Paris Museum.? 

lAll measurements are in millimeters ; specimens measured in the flesh 
unless otherwise stated. The basal length of the skull is measured from gna- 
thion to basion.the palatal length from Henselion (posterior alveolus of incisor) 
to palatal notch. 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 39 

Distribution. — Arid tropical lowlands and adjacent mountains of 
southern Tamaulipas, northern Vera Cruz, eastern San Luis Potosi, 
eastern Qiieretaro and Puebla, northeastern Hidalgo, and thence south 
to border of Humid Tropical zone in central Vera Cruz, and northern 
side of Isthmus of Tehuantepec in Oaxaca. (Usually below 4000 ft. 
alt., but sporadically up to over 8000 ft. in Hidalgo and Queretaro.) 
Characters. — Size large ; color of back pale grizzled gray with nape 
patch poorly defined, rusty or yellowish brown; underparts bright 
ferruginous, this color extending up over fore legs and costal area 
nearly or quite to top of shoulders. Tail long, flat, and rather slender; 
hairs on back rather coarse and glossy. Teats : p. \ a.| i. \. 

Color. — Top of nose and fore part of crown iron gray ; nape patch 
often indistinct and varying from dull yellowish brown to dull rusty 
rufous, generally grizzled with gray or whitish; rest of upperparts in- 
cluding upper cheeks, sides and top of neck (below and behind nape 
patch) a median line between shoulders, entire lumbar region, rump 
and outside of thighs varying from dark iron gray to pale whitish gray ; 
fore feet and sometimes outside of fore legs iron gray, usually darker 
than back ; hind feet varying from blackish faintly grizzled with gray to 
iron gray like back ; sides of nose, lower cheeks and chin pale grizzled 
gray ; rest of underparts bright ferruginous, this color usually extend- 
ing over outside of fore legs and high up over costal area, sometimes 
even meeting and forming a band across top of shoulders ; base of tail 
all around like back; rest of tail above black washed with white; be- 
low, with a broad median band of ferruginous, bordered by a line of 
black and edged with white ; ring around eye dark buff, with an area 
of dull yellowish brown extending back nearly or quite to base of ear ; 
ears gray like crown, or rusty reddish like nuchal patch ; ear patches 
(usually absent in summer) dingy gray or whitish. Hairs on back 
black, with broad white tips, often mixed with others having broad 
median and sometimes basal yellow rings. The winter pelage differs 
from that of summer mainly in paler upperparts and distinct whitish 
ear patches. 

Variation. — Sciurus atireogaster presents a wide range of varia- 
tion. The underparts range from bright ferruginous to dark ru- 
fous, almost like the color of S. hypopyrrhus. The back varies 
from whitish to dark iron gray. The upward extension of ferrugi- 
nous on the sides varies from a slight wash just back of fore legs to 
a broad band reaching over costal area and across top of shoulders, 
covering nearlv half of the body. 

A specimen from Orizaba in the U. S. National Museum has the 



40 



NELSON 



rufous reaching up all along the flanks, covering the outside of thighs 
and back, and confining the gray dorsal area to a median band on lum- 
bar region and rump ; the top of head and nape black, thinly grizzled 
with gray, and the tail black thinly washed with gray above, and with 
ferruginous along middle of under side. A specimen from Pinal de 
Amoles, Qixeretaro, has the upperparts, including outside of legs, 
sides of body and upper surface of tail, nearly uniform pale grizzled 
gray; the underparts dingy rusty. A specimen from Catemaco, Vera 
Cruz (approching hypopyrrhus in intensity) has the same pattern as 
the one last described, but the breast and inguinal region are grizzled 
with gray. The width of the red median band on the under side of 
tail varies and is sometimes nearly or quite replaced by the widening of 
the black border. This is a common phase in individuals grading to- 
ward kypopyrrkus. Specimens from northern Vera Cruz, Queretaro, 
San Luis Potosi, and Tamaulipas are paler or gi'ayer than those from 
farther south in central Vera Cruz. 

On the east slope of the Cofre de Perote near Jico and Jalapa, 
Vera Cruz, most of the squirrels are intergrades between aureogaster 
proper a.\\d J'ru??2entor . They are even richer ferruginous below than 
true aureogaster, but have the distinct nape and rump patches and 
tendency to obsolescence of rufous median band on lower side of tail 
oifrumentor. On account of the rufous underparts these specimens 
are referred to aureogaster rather than to jfrti mentor \ they combine 
the characters of the two forms in about equal proportion but dif- 
fer slightly from either. Squirrels from Lake Catemaco, Vera Cruz, 
and about Guichicovi, Serabia, and Santo Domingo, Oaxaca, on the 
Isthmus of Tehuantepec, show intergradation between true anreo- 
gaster and hypopyrrhus, and it is frequently puzzling to decide on 
which side of the line to class them. 

Melanism is common in this species; it is particularly prevalent in 
some localities and at times entirely replaces the normal phase. A 
melanistic specimen from Alta Mira, Tamaulipas, has the top of the 
head and rest of upperparts dark rusty brown, thinly washed with 
black, darkest over the shoulders ; tail black slightly washed with gray ; 
entire underparts, including nose and sides of head to eyes, fore feet 
and legs and hind feet black, and a thin collar of grizzled rusty brown 
across the under side of neck. A specimen from Forlon in the same 
state is similar but has a very much heavier wash of black on the back. 
Very young squirrels show the characteristic color markings. 

Measurements. — Average of 5 adults from Alta Mira : total length 
509 ; tail 260 ; hind foot 66.6. 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 4 1 

Cranial characters. — Premolars \ . The skull (pi. I, fig. 9) of 
this species is typical of a large group of squirrels in Mexico and Cen- 
tral America. It is rather short and robust, with heavy rostrum ; the 
braincase is inflated over the interparietal region; the peg-like ist pre- 
molar is set barely inside and close to the anterior angle of the 2d 
premolar. Five adult skulls from Alta Mira average : basal length 
49.8 ; palatal length 26.5 ; interorbital breadth 19.1 ; zygomatic breadth 
34.5; length of upper molar series 11. 3. 

General notes. — This strikingly colored species was the first tree 
squirrel of Mexico and Centi"al America to receive a distinctive scien- 
tific name, and has figured most prominently in scientific literature. 
Cuvier published an excellent figure of it with the original description, 
showing the characteristic bright rufous underparts. The figure repre- 
sents the less common phase of pelage with but slight extension of ru- 
fous on the costal area and a poorly defined nuchal patch. By some 
curious oversight Cuvier, two years later, renamed the species S, leuco- 
gaster. He gave California as the habitat of this squirrel but men- 
tioned specimens from eastern Mexico; modern explorations have 
proved conclusively that it occurs only in eastern Mexico. Later 
authors have placed it under various names, among which Sciurus 
variegattts Erxleben has been frequently used, but as I have recently 
shown (Science, NS., viii, No. 208, pp. 897-8, Dec. 23, 1898), 
the latter name belongs to a ground squirrel — the so called Spermo- 
fhilus macrourus of Bennett and other authors. The Scuirus ferru- 
giniventris of Audubon and Bachman is unmistakably the same as 
Cuvier's aureogaster., and like it was said to come from California ; 
and there is little doubt that S. mustelimis of the same authors was 
based on a melanistic specimen of the same animal. 

Sciurtts aureogaster is separable into three well marked geographic 
races, of which the one most closely agreeing with Cuvier's figure and 
description inhabits northern Vera Cruz and southern Tamaulipas. 
Hence specimens from Alta Mira in southern Tamaulipas are here de- 
scribed as typical. 

Habits. — This squirrel has a wide distribution in the forests of 
eastern Mexico, ranging from the coastal plains to the slopes of the 
Cordillera. On the northern side of the Isthmus of Tehuantepec, 
Oaxaca, as well as near Orizaba and Jalapa, Vera Cruz, and farther 
north it commonly ranges up to an altitude of 4000 feet. 

Still farther north it extends back along the deep river valleys far 
into the interior of Hidalgo and Qiieretaro ; and on the humid, 
densely forested slopes of the mountains at Pinal de Amoles, Qiiere- 



42 NELSON 

taro, and near Encarnacion, Hidalgo, Mr. Goldman took specimens 
at an altitude of over Sooo feet. The northern part of its range is an 
arid tropical region where it occurs mainly in heavy woods along 
streams and canyons. Farther south, on the borders of the humid 
tropical region, it finds suitable forests more generally distributed ; and 
on the mountain slopes it is usually found in areas of heavy tree growth. 

Throughout their range these squirrels do considerable damage to 
cornfields, and while corn is in the ear it is an easy matter to find 
them about the edges of fields cleared in the forest. At other times 
they are dispersed, seeking food wherever wild fruits or nuts may be 
in season. Their occurrence at an altitude of Sooo feet in Hidalgo 
and Queretaro is probably due to a migration in search of food, for 
this is far above their usual I'ange. 

Speci7nens exami7icd. — Ninety-eight, from the following localities : 
Victoria, Forlon and Alta Mira, Tamaulipas ; Valles, San Luis 
Potosi ; Pinal de Amoles, Qiieretaro (8000 feet) ; Metlaltoyuca, 
Puebla ; Sierra Encarnacion, Hidalgo (8000 feet) ; Papantla, 
Chichicaxtle, Jalapa, Jico, Mirador, Orizaba, Motzorongo, Otatitlan, 
Tuxtla, and Catemaco, Vera Cruz ; Serabia, Guichicovi, and 
mountains near Santo Domingo, Oaxaca. 

SCIURUS AUREOGASTER HYPOPYRRHUS (Wagler). 
Fire-bellied Squirrel. 

Sciurus hypopyrrhus Wagler, Oken's Isis, pp. 510-51 1, 1831 ; Wagner, 
Schreber's Saugth., 11, Suppl. pi. ccxiii c, 1837; Ibid., Suppl., iii, pp. 
167-168, 1843 ; Saussure, Revue et Mag. deZooL, p. 5, 1861 ; Allen, 
Mon. N. Am. Rodentia, pp. 746-750, 1877 (part) ; Alston, Proc. Zool, 
Soc. London, pp. 662-664, 1878 (part) ; Biol. Cent. -Am. Mammalia, pp. 
1 28-131, 1880 (part : specimens from Coatzacoalcos, Vera Cruz). 

Sciurus hyPopyrrhous Gray, Ann. & Mag. Nat. Hist., 3d ser., xx, p. 424, 
1867. 

Macroxus morio Gray, Ann. & Mag. Nat. Hist., 3d ser., xx, p. 424, 1867. 

Macroxtis maurus Gray, Ann. & Mag. Nat. Hist., 3d ser., .xx, p. 425, 1867. 

Sciurus variegatics '^MiAiCYi.v.KST, La Naturaleza, v, p. 324, 1882 (part: speci- 
mens from southern Vera Cruz, Mexico). 

Sciurus rufiventris} RoviROSA, La Naturaleza, vii, p. 360 (1885-86) 1887 
(Tabasco, Mexico). 

Sciurus aureogastcr Allen, Bull. Am. Mus. Nat. Hist., iii, pp. 1 81-182, 
1890 (part : specimens from Serabia, Oaxaca). 

Type locality. — ' Mexico.' Specimens from Minatitlan, Vera Cruz, 
are typical. Location of type specimen unknown — but probably in 
Berlin Museum. 

Distribution. — Humid tropical forests of southern Vera Cruz, ad 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 43 

jacent parts of extreme southeastern Oaxaca, Tabasco, eastern Chia- 
pas, and perhaps extreme northwestern Guatemala (below 4000 feet). 

Characters. — This form is much darker than true 6". aureogaster\ 
the intense, almost chestnut rufous of underparts usually extends as a 
broad band over the costal area and top of shoulders; the pelage is 
thinner, with much stiffer and more shining dorsal hairs, and the tail 
slenderer with black predominating. Teats: p. \ a. %\.\. 

Color. — Top of nose and fore part of crown dark iron gray; lum- 
bar region, rump, outside of thighs and base of tail finely grizzled 
with black, grayish white, and dull rusty or yellowish brown ; nape 
patch indistinct, dull yellowish brown or dingy rufous, often grizzled 
with black and gray; ears like nape, grizzled gray or reddish brown, 
sometimes bordered with black ; a thin basal patch of dingy grayish 
white in winter; ring around eyes reddish or dark buffy brown, 
confluent with area of same color extending back on sides of head 
below ears; sides of nose, chin, and most of cheeks dingy gray; rest 
of underparts deep, almost chestnut ferruginous, the same color 
usually covering all of fore legs and extendmg up as a broad band 
over costal area and shoulders ; fore and hind feet black, sometimes 
minutely grizzled with gray ; tail above, black thinly washed with 
white ; below, usually with a narrow median line of rich ferruginous, 
heavily bordered with black and thinly edged with white, the median 
rufous line frequently absent and replaced by black. Hairs on 
back (except rufous area) black, with fine tips of white or some- 
times narrow subterminal rings of yellowish brown. 

Variation. — Black squirrels of this form are very common at 
Minatitlan and in Tabasco. A curious specimen from Minatitlan is 
uniformly black except on sides of nose, cheeks and chin which are 
dark gray ; flanks and hips thinly grizzled with yellowish gray ; upper 
surface of tail thinly grizzled with gi"ay ; underparts, including inside 
of legs, dark reddish brown. The nuchal patch is sometimes 
confluent with the rufous area on shoulders, though usually lighter. 
An immature specimen from the vicinity of Santo Domingo, Oaxaca, 
is dingy reddish brown above, grizzled with black and gray. The 
area covered by rufous on sides and across shoulders varies, and 
the color also varies in intensity. The forelegs are sometimes grizzled 
iron gray with or without mixture of reddish. 

Measureme7its. — Average of 5 adults from Minatitlan : total 
length, 522.8; tail vertebrae, 266.8; hind foot, 67.3. 

Cranial characters. — Premolars f . Skull similar to that of typi- 
cal aureogaster but larger and proportionately narrower, with audital 



44 



NELSON 



bulltE larger and slightly constricted just in front of middle. Five 
adult skulls from Minatitlan average: basal length, 52.6; palatal 
length, 27.1; interorbital breadth 1S.4; zygomatic breadth, 34.8; 
length of upper molar series 11.4. 

General notes. — Although Wagler merely gave 'Mexico' as the 
type locality for S. hypopyrrhus., his description applies so well to the 
dark colored race of S. aiireogaster of southern Vera Cruz that it 
seems advisable to adopt his name for this form. Specimens from 
Minatitlan, Vera Cruz, are typical. 

An adult from Minatitlan (No. 780S2 9 ad., U. S. Nat. Mus.) 
is even darker and more generally ferruginous than the Santo Domingo 
specimen, and has a blackish area on fore shoulders and blackish rump 
finely grizzled v\^ith dingy yellowish. After comparing this specimen 
with the type of Macroxus maurus Gray, Mr. Thomas writes that it 
is exactly like one of the two co-types. He also states that the British 
Museum has a specimen from Teapa, Tabasco, similar to the type of 
Macroxus morio Gray, but a little less melanistic, and that this speci- 
men is the same as our No. 780S2 except for a little dash of melanism 
across the shoulders, thus proving the identity of maurus and tnorio. 

The name hypopyrrhus Wagler has been used indiscriminately by 
various authors for the rufous bellied squirrels of Mexico, Central 
America and even northern South America. 

Habits. — The Fire-bellied Squirrels live in the humid tropical forest 
where they range from sea level up to an altitude of about 4000 feet. 
They levy a heavy toll upon cornfields planted in clearings in the 
forest, and are also fond of cacao beans, gathering about the planta- 
tions in large numbers, and are especially destructive in Tabasco and 
eastern Chiapas. In order to gather a cacao crop the planters are 
obliged to employ men with guns to patrol the plantations daily, but 
in some districts, despite such efforts, the squirrels are a serious pest 
and do great damage. 

Specimens examined. — Eighteen : from Minatitlan and Catemaco, 
Vera Cruz ; mountains near Santo Domingo and Guichicovi, Oaxaca ; 
Uspanapa River, Tabasco; Tumbala, Chiapas. 

SCIURUS AUREOGASTER FRUMENTOR Nelson. 

Perote Squirrel. 

Sciurus aiireogaster fnimentor Nelson, Proc. Biol. Soc. Washington, xii, pp. 
154-155. June 3, 1898. 
Type locality. — Las Vigas, Vera Cruz, Mexico. Type no. 54259 
U. S. National Museum, Biological Survey Collection. 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 45 

Distribution. — Mixed pine and oak forests of Upper Austral zone 
on east and north base of the Cofre de Perote and adjacent eastern 
slope of the Cordillera near Las Vigas, Vera Cruz (alt. 6000-8000 ft. ) . 

Characters. — Differs strikingly from typical aiireogaster in having 
well marked nuchal and rump patches of yellowish brown or rufous 
brown; the underparts gray or gray washed with rufous; tail heavier 
and more bushy; pelage softer. Teats: p. i a, f i. \. 

Color. — Nuchal and rump patches strongly marked, varying from 
dark yellowish brown to dark rusty red, washed with black, extending 
forward as a paler area along sides of head to enclose ears and eyes; 
rest of upperparts including nose and fore crown, fore feet, outside 
of legs and sides of body, dark grizzled iron gray, usually with rusty 
or pale rufous subterminal rings on hairs of back and sides ; hind feet 
varying from black, slightly grizzled with gray, to dark iron gray; 
chin, throat and cheeks dingy gray ; rest of underparts varying from 
pale gray to gray washed with rusty red ; tail at base like back, rest of 
tail above black thinly washed with white ; below, with a median band 
varying from pale rusty yellowish to dark ferruginous, bordered with 
a black band and edged with white ; ears usually like nuchal patch but 
sometimes grayish and sometimes with a black border ; basal patch 
dingy white, present in winter, usually absent in summer. Hairs on 
back black, with conspicuous white tips often mixed with others hav- 
ing pale rufous subterminal rings. 

Variation. — The series of this form and of aiireogaster show per- 
fect intergradation although the two extremes are strikingly different. 
Some specimens taken below Las Vigas have the ferruginous of the 
underparts somewhat grizzled with gray and more dingy than in 
aureogaster. The black on the lower surface of the tail varies from 
a narrow border to a broad band which reduces the median area to a 
narrow line. Some specimens show 3 or 4 distinct black and rusty, 
or reddish, annulations on lower surface of tail, giving a grizzled ap- 
pearance which does not occur in either aureogaster proper or hypo- 
pyrrhus. No melanistic specimens seen. 

Measurements. — Average of 5 adults from type locality: total 
length 504.6; tail vertebrae 249.2; hind foot 68. S. 

Cranial characters. — Premolars f. Skull indistinguishable from 
that of typical aureogaster. Four adult skulls from the type locality 
average: basal length 52.5; palatal length 26.1 ; interorbital breadth 
19.7; zygomatic breadth 34.4; length of upper molar series 11. 2. 

General notes. — In several characters this subspecies agrees with 
the description of 6*. nigrescefis Bennett, but after comparing a speci- 



46 NELSON 

men of frjimcntor with Bennett's type, Mr. Thomas writes that they 
are not the same. 

Habits. — This form, like true aureogaster^ gathers about corn fields 
to feast upon the ripening ears. At other seasons it feeds mainly 
upon acorns and pine nuts, moving from one locality to another with 
the variation in food supply. 

Specimens exatnined. — Fourteen : from near Las Vigas and above 
Jico, Vera Cruz, Mexico. 

SCIURUS POLIOPUS (Fitzinger). Oaxaca Squirrel. 

Scitiriis albipes Wagner, Abhandl. math.-phys. CI. K. bayerisch. Akad. 

Wiss. Miinchen, 11, pp. 501-504, 506-507, 1837 ; Suppl. pi. ccxiii D, 

Schreber's Saiigthiere, 1837 (not .S". albipes Kerr, 1792). 
Sciurus variiis Wagner, Supplement Schreber's Saugthiere, iii, pp. 168-170, 

1843 (see Suppl. pi. CCXIII d, 1837). Not S. varius Pallas, 1831. 
Sciurus variegatus poliopiis Fitzingek, Sitzungsber. K. K. Akad. Wiss. 

Wien. math.-naturw. CI., LV, I. Abath., p. 478, March, 1867. (Based 

on .S". varius var. /? Wagner, I.e. iii, p. 168, 1843.) 
Sciurus variegatus rufipes Fitzinger, Sitzungsber. K. K. Akad. Wiss., Wien. 

math.-naturw. CI., lv, I. Abth , p. 478, March, 1867. (Based on S. 

varius var. y Wagner, I.e. iii. p. 168, 1843.) 
Macroxus leucops Gray, Ann. & Mag. Nat. Hist., 3d ser. , xx, pp. 427-428, 

Dec, 1867. 
Sciurus variegatus Alston, Proc. Zool. Soc London, 1878, pp. 660-662 ; 

Biol. Cent. -Am., Mamm., pp. 127-128, 1880 (part: Oaxaca and La Pa- 

rada, Oaxaca). 
Sciurus 7vagneri h\JV.^'^, Bull. Am. Mus. Nat. Hist., N. Y., x, pp. 453-454, 

Nov., 1898. 

Type locality. — Cerro San Felipe, Oaxaca, Mexico. Type in 
Berlin Museum. 

Distributio7i. — Pine and oak forests of Transition and Boreal zones 
on mountains north, east, and south of Valley of Oaxaca, Mexico 
(alt. 7500-11,000 feet). 

Characters. — Size large ; back grizzled gray ; underparts bright 
ferruginous; feet white. Pelage thick and soft; tail large and bushy. 
Teats : p. \ a. | i. \. 

Color. — Top of nose and fore crown iron gray ; nape patch rather 
indistinct, yellowish brown washed with black; rump patch, when 
present (usually absent), of same color; rest of back and outside of 
fore and hind legs gray, more or less plentifully intermixed with hairs 
having yellowish or rusty brown subterminal rings ; feet usually pure 
white ; ears gray or mixed gray and brown, with well marked white 
basal patches : sides of head gray, or grayish white, paler than back ; 
ring around eyes whitish ; chin and throat white or grayish white ; 
rest of vmderparts rich ferruginous red ; tail at base all round like 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 47 

back; tail above black, washed with white; below, with well defined 
broad median area varying from grizzled yellowish or rusty brown to 
clear ferruginous, narrowly bordered with black and edged with 
white. Hairs of back black with white tips and basal, median or 
subterminal rings of rufous. 

Variation. — Most of the series from Cerro San Felipe, Reyes, and 
Mt. Zempoaltepec agree in having the feet white. When the nape 
patch is well defined the area between the eye and base of ear is usually 
yellowish brown. 

A Zempoaltepec specimen is brighter rufous below, and the reddish 
buffy rings of the dorsal hairs are brighter and more conspicuous than 
usual. The three specimens from the vicinity of Ozolotepec, at the 
southeast end of the Valley of Oaxaca, are in winter pelage and differ 
from summer specimens from the Cerro San Felipe in having the sides 
of the head and ring around eye shaded with dark buffy, and the feet 
grizzled gray. The squirrels from near Ozolotepec live in an isolated 
group of mountains, though not distant from the range of which the 
Cerro San Felipe forms a part, and probably represent a local form 
not sufficiently differentiated to warrant subspecific recognition. A 
single specimen from Cerro San Felipe, with feet grizzled gray, repre- 
sents Wagner's var. ^ {=. S. variegatus foliopus Fitzinger) ; and an- 
other with feet white suffused with rufous represents Wagner's var. 
f (^=. S. variegatiis rujipe'!^ Fitzinger) showing that these forms were 
based upon individual variation. Apparently there is no striking differ- 
ence between summer and winter pelages. No melanistic specimens 
seen. 

Measurements. — Average of five adults from type locality : total 
length 527.6; tail vertebra 257.6; hind foot 70.2. 

Cranial characters. — Premolars \. Skull (pi. II., fig. 3) more 
slender and rostrum longer than in typical S. aureogaster. Five adult 
skulls from the type locality average : basal length 52.2 ; palatal length 
27.3; interorbital breadth 18.6; zygomatic breadth 34.5; length of 
upper molar series 10.7. 

General notes. — In 1S37 Wagner named this squirrel Sciuriis 
albipes.1 and in 1843 replaced this name by S. varitcs, mentioning two 
varieties, var. /5("pedibus nigro-cinereis ") and var. ^ ("pedibus fer- 
rugineis"). In March, 1867, Fitzinger named these varieties respec- 
tively Sciurus variegatus polioptis and Sciurus variegatus rufipes., 
and in the following December Gray named the species Macroxus leu- 
cops. Recently Dr. J. A. Allen has shown that both of Wagner's 

Proc. Wash. Acad. Sci., April, 1899. (4?) 



48 



NELSON 



names were preoccupied and, overlooking Fitzinger's names, renamed 
the species S. tvagneri} 

A typical specimen of S. poliopus (No. 68183 U. S. Nat. Museum) 
from Cerro San Felipe, was sent to the British Museum for compari- 
son with the type of Gray's Macroxus leucops^ and Mr. Thomas in- 
forms me that it is exactly like one of the two cotypes (B. M. 58. 10. 
23.4.) ; the other cotype differs only in being rather less rufous and not 
so gray. 

Wagner's specimens were obtained by Karwinski, a botanical col- 
lector who did much work on the Cerro San Felipe (a few miles north 
of the city of Oaxaca) and as the original descriptions apply perfectly 
to the squirrels of this part of the Cordillera of Oaxaca it is unques- 
tionably the type locality. 

Speci?nens exa7nhied. — Sixteen : from Cerro San Felipe, Reyes, 
Mt. Zempoaltepec, mountains near Ozolotepec, and Pluma, Oaxaca. 

SCIURUS POLIOPUS HERNANDEZI Nelson. 

Oak Woods Squirrel. 

Sciurus aJbipes quercinus Nelson, Proc. Biol. Soc. Washington, xii, pp. 15a 

151, June, 3, 1898 (not 6". quercinus Erxl., 1777). 
Sciurus wagneri quercinus Allen, Bull. Am. Mus. Nat. Hist., N. Y., x, p. 

453, Nov., 1898. 
Sciurus a/bipes /lernandezi NEhSOii, Science, NS.,viii, p. 783, Dec. 2, 1898. 

Type locality. — Mountains 15 miles west of City of Oaxaca, 
Oaxaca, Mexico. Type no. 68202, U. S. National Museum, Bio- 
logical Survey Collection. 

Distribution. — Pine and oak forests of Transition and Boreal zones 
on mountains west of the Valley of Oaxaca and thence to Lower 
Sonoran zone in southern Puebla and southeastern Guerrero, Mexico. 

Characters. — Back grayer than in S. poliopus., and intermixed with 
yellow instead of rufous ; underparts white or buffy ; median band on 
lower surface of tail usually grizzled yellowish gray. Pelage thick and 
soft; tail large and bushy. Teats: p. l a. f i. \. 

Color. — Top of nose and fore part of crown grizzled gray washed 
with blackish ; nape usually faintly yellowish, grizzled with black ; 
rump patch rarely present ; rest of upperparts, including outside of 
legs, pale gray mixed with pale yellowish; feet white; ears gray or 
mixed gray and yellowish brown with well marked white basal patch ; 
sides of head dingy grayish, sometimes shaded with brown between 
eye and ear; ring around eye whitish; tail all around at base like 

iBull. Am. Mus. Nat. Hist., N. Y., X., pp. 453-4, Nov. 10, 1898. 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 49 

back ; tail above black, heavily washed with white ; below, with 
broad median band varying from dingy grizzled yellowish gray to 
pale rusty, a poorly defined black border and broader edging (and 
sometimes wash over entire lower surface) white ; chin and throat 
white; rest of underparts usually white, sometimes varying to pale 
buffy or rusty buff. Hairs on back black with white tips and yellow- 
ish basal rings, mixed with others having subterminal and basal rings 
of dull yellowish, and still others with black subterminal, and yellow- 
ish median rings. 

Variation. — The yellowish ringed hairs on the back vary somewhat 
in number but are not sufficiently numerous to appreciably effect the 
general color. A faint yellowish indication of the rump patch is some- 
times present, but always indistinct. No melanistic specimens seen. 
Specimens from the arid Lower Sonoran and upper edge of the Arid 
Tropical zones in northwestern Oaxaca, southwestern Puebla, and ad- 
jacent part of Guerrero are closely related to herna?idezi, but are 
slenderer with backs whiter, nape and rump patches more distinctly 
yellowish brown ; underparts usually buffy but sometimes white, and 
median area on underside of tail bright rusty ferruginous. The char- 
acters presented by these squirrels are almost worthy of subspecific 
recognition, but the material at hand is too limited to satisfactorily de- 
termine their value. 

Measurements. — Average of five adults from type locality : total 
length 539.6; tail vertebrae 268.8; hind foot 68.8. 

Cranial characters. — Premolars \. Skulls average a little smaller 
(with longer upper molar series) but are not otherwise distinguishable 
from those of S. poliopus. Five from type locality average : basal 
length 51.5; palatal length 26.5; interorbital breadth 19.5; zygomatic 
breadth 34.6; length of molar series 11. 

General notes. — The name first proposed for this squirrel being 
preoccupied, the subspecies was i"enamed in honor of Francisco Her- 
nandez, the author of the Historise Animalium Novs Hispaniae. 

Habits. — These squirrels feed upon acorns and pine nuts, and at 
the time of our visit to the type locality, in September, were found in 
the huge oak trees growing along certain slopes and ridges in the pine 
forest at an altitude of 8000-9000 feet. They were shy, and instead 
of concealing themselves at our approach, usually made off through 
the tree tops. 

Specimens examined. — Twenty-one : from mountains west of Val- 
ley of Oaxaca, southwestern Puebla and southeastern Guerrero. 



50 NELSON 

SCIURUS POLIOPUS NEMORALIS Nelson. 

Michoacan Squirrel. 

Sciurus albipes nemoralis Nelson, Proc. Biol. Soc. Washington, xii, p. 151, 

June 3, 1898. 
Sciiirus wagneri nemoralis h.ix.'E^, Bull. Am. Mus. Nat. Hist., N. Y., x, p. 

454, Nov., 1898. 

Type locality. — Patzcuaro, Michoacan, Mexico. Type no. f flff? 
U. S. National Museum, Biological Survey Collection. 

Distribution. — Pine and oak forests of Transition and Boreal 
zones, from the Volcano of Toluca, State of Mexico, to Nahuatzin, 
Michoacan, Mexico (alt. 7000-12,000 feet). 

Characters. — Similar to .S. hernatidezi in having feet and under- 
parts vs^hite, but back, including nape and rump patches, decidedly 
darker. Pelage full and soft ; tail lai-ge and bushy. Teats : p. i a. f 

Color. — Top of nose and fore crown dark iron gray washed with 
shining black ; nape patch usually varying from dingy yellowish brown 
to dark rusty, almost chestnut brown, washed and grizzled with black ; 
rump patch usually paler; rest of upperparts, including outside of 
legs, iron gray with slight intermixture of rusty ; feet usually white ; 
ears dark gray or grizzled gray and yellowish brown, with distinct white 
basal patches ; sides of head whitish gray ; ring around eye whitish ; 
sides of head from nape patch to eyes sometimes yellowish brown ; 
underparts usually white, rarely buffy yellow ; tail above black, with 
heavy wash of white ; below, with broad median area grizzled gray, 
yellowish gray or yellowish brown, with poorly defined black border 
and white edge, the white sometimes extending as a wash over entire 
lower surface. Hairs of back black, with subterminal and sub-basal 
rings of dark buffy or yellowish, or with white tips and basal, or sub- 
terminal, buffy rings. 

Variation. — The nape and rump patches vary from dingy yellowish 
to dark buffy or dingy chestnut, washed more or less heavily with 
black ; nape usually darker than rump. A melanistic phase occurs at 
Patzcuaro and becomes more common to the southeast until on the 
Volcano of Toluca it entirely replaces the gray phase. Only two out 
of nine melanistic specimens from Toluca are grizzled with dingy 
yellowish gray, the others being uniformly black. Some of the six 
melanistic specimens from Patzcuaro are sparsely and others abun- 
dantly grizzled with gray or dingy fulvous, and the tail is strongly 
edged with white. In the latter specimens the under sui-face is usually 
smoky black, and one has albinistic patches in the axillae and on the 



SQIJIRRELS OF MEXICO AND CENTRAL AMERICA 5 1 

belly. An immature female from Patzcuaro has the feet gray, but 
this is rare. Only three of the large series in the gray phase from 
Patzcuaro have buff underparts. The amount of intermixed rusty on 
the back varies but is never strong enough to affect the general color. 

Measu7-ements. — Average of five adult specimens from type 
locality : total length 537 ; tail vertebrae 273 ; hind foot 6"^.%. 

Cranial characters. — Premolars f-. Skulls not distinguishable 
from those of S. poUopus. Three adult skulls from the type locality 
average: basal length 51; palatal length 26.8; interorbital breadth 
18.6; zygomatic breadth 34.3; length of upper molar series 11. 

Habits. — These squirrels feed upon acorns and pine seeds accord- 
ing to the season, and are not so shy as some of their relatives. They 
vv^ere common near Patzcuaro and on the Volcano of Toluca. 

Specimeiis cxainined. — Thirty-two : from Patzcuaro and Nahuatzin, 
Michoacan, and north slope Volcano of Toluca, Mexico. 

SCIURUS POLIOPUS CERVICALIS (Allen). 
Colima Mountain Squirrel. 

Sciierus leucops Allen, Mon. N. Am. Rodentia, pp. 753-756, 1877 (part : 
specimens from Sierra Madre of Colima — not ^S". leucops Gray, 1867). 

Sciurus variegatus Ai^syo^, Biol. Cent. -Am., Mammalia, pp. 127-128, 1880 
(part : specimens from " Durango, Xantus, U. S. Nat. Mus." ; really 
from the Sierra Madre of Colima. Not S. variegatus Erxl., 1777). 

Sciiirus atireoo;astcr leucops Allen, Bull. Am. Mus. Nat. Hist., N. Y., 11, pp. 
1 66-1 67,'' Oct., 1889. 

Schirus ccrjncalis Allen, Bull. Am. Mus. Nat. Hist., N. Y., in, pp. 183- 
185, Dec, 1890, 

Sciuriis wagncri cervicalis Allen, Bull. Am. Mus. Nat. Hist., N. Y., x, p. 
454, Nov., 1898. 

Type locality. — Hacienda San Marcos, Tonila, Jalisco, Mexico 
(at east base of Sierra Nevada de Colima). Type no. 1991, 
American Museum of Natural History, New York. 

Distribution. — Pine and oak forests of Upper Austral and Boreal 
zones of the Sierra Nevada de Colima, Jalisco, Mexico, and thence 
north along high mountains to Ameca, Jalisco, and east into western 
Michoacan (alt. 6000-12,000 feet; sporadically down to 4000 ft.). 

Characters. — Readily distinguished from the other forms of 
S. poliopus by the dark iron gray upperparts, blackish head, dark nape 
and rump patches, and dark iron gray under surface of tail. Pelage 
thick and soft; tail large and full. Teats: p. j- ^- f ^- x- 

Color. — Top of nose and fore crown shiny black with grizzling of 
grayish white ; nape and rump patches usually distinct, dark fulvous 
or rusty brown heavily washed and grizzled with black ; rest of upper- 



52 NELSON 

parts, including outside of legs, dark iron gray (rarely intermixed 
with yellowish ringed hairs) ; feet similar but paler; ears dark grayish 
or yellowish brown with distinct white basal patch; sides of head 
dingy grayish ; ring around eye whitish ; area between eye and ear 
often suffused with brownish; underparts white, sometimes slightly 
grizzled with black; tail at base like rump; rest of tail, above black 
heavily washed with white ; below, a broad median line of grizzled 
dark iron gray bordered with black and edged with white, the white 
often forming a thin wash over under surface. Hairs of back usually 
black with white tips, but occasionally intermixed with others having 
a median ring of buffy. 

Variation. — Specimens from the type locality show comparatively 
little variation. The upperparts are sometimes paler or darker than 
in typical specimens and the wash of black on crown and rump is 
sometimes heavy enough to obscure the yellow patches. The feet 
vary from iron gray to whitish gray but are never white. Black al- 
ways predominates on lower side of tail but the amount of gray varies. 
Compared with typical specimens those from Ameca are paler on the 
back and lower surface of tail, and the nape and rump patches are 
more obsolescent. 

Measurements. — Average of five adults from type locality : total 
length 536; tail vertebra 267.2; hind foot 66.4. 

Cranial characters. — Premolars \. Skull indistinguishable from 
that of S. poliopus. Five adult skulls from near type locality aver- 
age : basal length 51.2; palatal length 27.6; interorbital breadth 
19.8; zygomatic breadth 34.9; length of upper molar series 11. 7. 

Habits. — These handsome squirrels have a wide vertical range 
In April they were found at an altitude of 4000 feet feeding on wild 
figs in the canyon near Plantinar, at the east base of the Sierra Nevada 
de Colima. On the north slope of the same mountain they were com- 
mon and feeding on acorns among scrubby oaks at 6000 feet, and we 
saw many gnawed pine cones at I2,cx)0 feet. Dr. Buller who col- 
lected the type took a specimen at the latter altitude on this mountain. 
Specimens examined. — Twenty-four : from Plantinar, Hacienda 
San Marcos and elsewhere on slopes of Sierra Nevada de Colima, 
and at Ameca, State of Jalisco. 

SCIURUS POLIOPUS COLIMENSIS Nelson. Colima Squirrel. 

Sciurus leucops Allen, Mon. N. Am. Rodentia, pp. 753-754, 1877 (part: 

specimens from Rio Coahuyana, Colima, Mexico). 
Sciurus albipes colimensis'^YX&Q'ii, Proc. Biol. Soc. Washington, xil, p. 152, 

June 3, 1898. 
Sciurus wagneri colitnensis Allen. Bull. Am. Mus. Nat. Hist., N. Y., x, p. 

454, Nov., 1898 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 53 



Type locality. — Hacienda Magdalena, Colima, Mexico, Type no. 
IMti* U- '^- National Museum, Biological Survey Collection. 

Distribution. — Arid tropical coast region in State of Colima, 
western J^lexico (below 2000 ft.). 

Characters. — Pelage thinner and tail more slender than in other 
subspecies of S. pollopus\ nape and rump patches well marked, rusty 
or yellowish brown; back gray mixed with considerable rusty; feet 
dark iron gray or blackish. Teats: p. \ a. I- i. \. 

Color. — Nape and rump patches distinct, varying from yellowish 
brown to dark rusty shaded with black ; nose and forecrown grizzled 
iron gray, sometimes suffused with yellowish brown extending forward 
from nape patch; rest of back rather pale grizzled gray, abundantly 
intermixed with rusty ringed hairs; outside of legs iron gray ; forefeet 
dark iron gray ; hind feet darker iron gray varying to black and thinly 
grizzled with gray; sides of head dingy grizzled gray, sometimes suf- 
fused with yellowish brown ; ring around eye dingy white or dull buff ; 
ears like nape, with small basal patch of dull whitish or dingy rusty ; 
underparts white; tail at base like back; rest of tail above black 
thinly washed with white; below, with broad median area dark 
grizzled iron gray (sometimes faintly washed with yellowish) bor- 
dered by black and thinly edged with white. Hairs of back black with 
white tips and basal, sub-basal or subterminal rings of buffy or rusty. 

Variation. — The upperparts vary from pale gray to iron gi'ay ; the 
feet are usually darker than the back, but sometimes paler. An imma- 
ture specimen from the type locality is pale gray with the rusty rump 
patch nearly obsolete. A female taken in February at Armeria has the 
inside of fore limbs, thighs, and sides of belly washed with buffy, and 
median area on under side of tail dark grizzled fulvous. The black 
border on lower surface of tail varies from a narrow line to a band 
half an inch wide. 

Measurements. — Average of five adults from type locality : total 
length 526; tail vertebrte 267; hind foot 67.6. 

Cranial characters. — Premolars |-. Skull somewhat smaller but 
not otherwise separable from that of typical S. poliop7is. Five adult 
skulls from near type locality average : basal length 502 ; palatal 
length 26.7; interorbital breadth 19. i ; zygomatic breadth 33. 8; length 
of molar series 11. 2. 

General notes. — Sciurus p. colimensis is most closely related to 
S. p. cervicalis^ but typical specimens are readily distinguished by 
paler backs and strongly marked reddish or fulvous nape and rump 
patches. The feet are darker chan in any of the other subspecies of 



54 NELSON 

poliopus and, with the exception of ^. p. effugius^ the nape and rump 
l^atches are more strongly contrasted with the rest of the back. 

Specimens examined. — Ten: from Hacienda Magdalena, Armeria, 
and Rio Coahuyana, Colima. 

SCIURUS POLIOPUS EFFUGIUS Nelson. Guerrero Squirrel. 

Sciiirns albipcs cffugius'^^i^^o^, Proc. Biol. Soc. Washington, xii, pp. 152- 

153, June 3, 1898. 
Sciurus wagneri effugius Allen, Bull. Am. Mus. Nat. Hist., N. Y., .x, p. 

454, Nov. 10, 1898. 

Type locality. — High mountains west of Chilpancingo, Guerrero, 
Mexico. Type no. 70288 U. S. National Museum, Biological Sur- 
vey Collection. 

Distribution — Pine and oak forests of Transition and Boreal zones 
along summit of Cordillera in southwestern Guerrero (alt. 7500- 
9500 ft.). 

Characters. — Back grizzled gray ; nape patch conspicuous, dark 
rufous ; ear patches large, white and more conspicuous than in any 
other form of the species ; underparts darker rufous than in poliopus ; 
median area on under side of tail deeper, richer rufous. Pelage thick 
and soft ; tail large and bushy. Teats : p. i a. |- i. i. 

Color. — Winter pelage : Nape patch rusty rufous, becoming almost 
rusty chestnut in some specimens ; top of nose iron gray intermixed 
with yellow ringed hairs ; rest of dorsal surface finely grizzled iron 
gray intermixed with rusty ringed hairs ; indications of a rump patch 
similar in color to nape sometimes present but heavily overlaid with 
grizzling of white and black ; extension of nape patch over sides of 
head, including bases of ears and eyes, slightly paler than main area ; 
ring around eye buffy or whitish ; ears reddish brown like crown, but 
sometimes grizzled with grayish ; basal ear patches very large and 
brilliantly white ; outside of legs gray, usually with less mixture of rusty 
than on back; feet white, often washed with pale rufous; tail at base 
like rump ; rest of tail above black, heavily washed with white (with 
rufous under color showing through) ; below, with broad median area 
nearly pure i-ich dark rufous, narrow black border, and thin white 
edge ; chin and throat white ; rest of underparts rich dark rufous. Hairs 
on back black, with short white tips and either basal, sub-basal, or 
median rings of rufous. 

Variation. — One topotype has the nape patch extending over 
shoulders and costal region, rest of back strongly suffused with rusty, 
and a wash of same color on outside of fore legs and feet; another. 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 55 

probably representing a much worn phase of the summer pelage, has 
very distinct well defined nape and rump patches of rusty brown ; top 
of nose and back, including outside of legs and feet, pale iron gray 
with very indistinct rusty rings on intermixed hairs ; chin and throat 
white; underparts pale dull rusty washed with dingy white. 

Measurements. — Average of five adults from type locality : total 
length 496. 8 ; tail vertebrae 249 ; hind foot 6S. 

Cranial characters. — Premolars \. Skulls average a little smaller 
but are otherwise like those of S. poUopiis. Four adults skulls from 
the type locality average : basal length 50.9; palatal length 26.9; in- 
terorbital breadth 19.1; zygomatic breadth 34.5; length of upper 
molar series 1 1 . 

Habits. — In December we found these squirrels feeding on acorns 
of the large oaks among the pines on top of the Cordillera, but the 
abundance of gnawed cones scattered on the ground showed that at other 
seasons pines furnish their chief food supply. They were extraordi- 
narily shy and cunning, and it was very difficult to secure specimens. 

Specimens examined. — Eight : all from the type locality. 

SCIURUS NELSONI Merriam. Nelson's Squirrel. 
Sciiirus «^Zy£'«z Merriam, Proc. Biol. Soc. Washington, viir, p. 144, Dec. 1893. 

Type locality. — Huitzilac, Morelos, Mexico. Type no. 5 11 57 U. S. 
National Museum, Biological Survey Collection. 

Distribution. — Oak and pine forests of Transition and Boreal zones 
in mountains on south and west sides of Valley of Mexico, and south 
side of Valley of Toluca, in the Federal District and States of Mexico 
and Morelos (alt. Sooo-i 2,000 ft.). 

Characters. — Body large and heavy ; back grizzled, sooty blackish 
brown ; feet black ; underparts grizzled blackish, sometimes washed 
lightly with dingy yellowish brown or rusty rufous. Pelage veiy thick 
and soft; under fur long; tail extremely broad and bushy. Teats: p. 

y a. 2 1. y. 

Color. — Upperparts sooty blackish usually washed or grizzled with 
dull yellowish brown; head usually darker than back and sometimes 
entirely black, shading gradually into color of back on nape ; ears, feet, 
and sometimes outside of fore legs and lower thighs black ; sides of 
head (when not black) grizzled blackish gray varying to dark yellow- 
ish brown; lower cheeks and chin grayer; underparts grizzled and 
varying from dingy blackish brown, thinly washed with dull yellowish, 
to dark brown washed with dull rusty ; tail at base all around like 
rump, rest of tail above black, washed with grayish white; below 



56 NELSON 

nearly uniform blackish with yellowish gray or brown showing through 
and thin edging of dingy white, but sometimes with median area very 
dark grizzledyellowish gray or yellowish brown, washed with black and 
narrowly edged with dingy white. Hairs on entire back black with 
narrow subterminal and broader basal or sub-basal rings of smoky buff 
or brown. 

Variation. — No melanistic specimens have been seen from the type 
locality, but two individuals from Tenango del Valle in the Bangs 
collection are nearly uniform black, having only a thin grizzling of 
dingy gray along the sides, and one has a pale wash of reddish brown 
on breast and belly. Another specimen in the same collection from 
Tenango differs in having a nuchal patch of dark grizzled reddish 
brown, contrasting with rest of back; feet pale buffy brown, toes 
dingy whitish ; rest of back normal, but entire underparts dull 
rufous, becoming darker posteriorly. One specimen from Ajusco also 
has the underparts similarly colored. 

Measureme7its. — Average of five adults from type locality : total 
length, 521.6; tail vertebrae, 262.6; hind foot, 67.6. 

Cranial characters. — Premolars \. Skull like that of S. aureo- 
gaster. Five adult skulls from the type locality measure : basal 
length 50.7; palatal length 26.7; interorbital breadth 19.4: zygomatic 
breadth 34.9; length of upper molar series 11.9. 

General notes. — Sciurus nelsoni is one of the most distinct of the 
Mexican squirrels and has a very limited distribution. It has a single 
subspecies which lives on the slopes of Mts. Popocatepetl and Iztac- 
cihuatl, and serves as a good illustration of the remarkable readiness 
with which the squirrels of tropical North America vary with climatic 
conditions. The area inhabited by S. nelsoni and S. ?telsoni hirtus 
are in the same life zone and not more than 75 miles apart. 6". nelsoni 
is much the darker of the two and its coloration is correlated with the 
somewhat greater rainfall of the area it inhabits. 

Specimens examined. — Eighteen : from Huitzilac, Morelos ; Salazar 
and Ajusco, Federal District; and Tenango del Valle, State of Mexico, 
Mexico. 

SCIURUS NELSONI HIRTUS Nelson. 
Mount Popocatepetl Squirrel. 

Sciiiriis ne/sojii hirtus Nelson, Proc. Biol. Soc. Washington, xii, pp. 153- 
154, June 3, 1898. 

lype locality. — Tochimilco, Puebla, Mexico. Type no. 55325 
U. S. National Museum, Biological Survey Collection. 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 57 

Distributiojt. — Oak and pine forests of Transition and Boreal zones 
on Mts. Popocatepetl and Iztaccihuatl, in States of Mexico, Puebla, 
and Morelos (alt. 8000 to 12,000 ft.). 

Characters. — Similar to ^. nelsoni but differs in having a dark 
iron gray area on middle of back, grizzled gray feet, and dingy fur- 
ruginous underparts. Pelage thick and soft ; under fur long; tail ex- 
tremely broad and bushy. Teats : p.i a. f i. i. 

Color. — Crown, nape, and rump dingy grizzled yellowish or gray- 
ish brown; top of nose, middle of back (often reaching down on out- 
side of legs) finely grizzled bluish gray; feet gray, toes paler; ears 
similar to crown, with conspicuous white basal patches; chin and 
lower cheeks dull gray; underparts dingy ferruginous; tail above, 
black heavily washed with white ; below, median area grizzled yellow- 
ish or rusty brown, with black border and thin white edge. Hairs on 
gray area of back black, with short white tips, scantily mixed with 
similar hairs having narrow median or subterminal rings of dull buffy. 

Variation. — The gray area is sometimes an enclosed spot on mid- 
dle of back and sometimes covers most of the upper surface ; the gen- 
eral color is lighter and less sooty than in nelsoni., and the wash on 
tail is white. The ferruginous of underparts varies from light rusty 
to dark dull rufous. One specimen from Tochimilco has black ears 
and feet and a small patch of gray on middle of back, but can be recog- 
nized at once by the other characters. Two winter specimens from 
Mt. Popocatepetl can be distinguished from summer specimens from 
Tochimilco by the general grayness of the upperparts. 

Measurements . — Average of five adults from type locality : total 
length 514.2; tail vertebrae 256.8; hind foot 6%. 

Cranial characters. — Premolars ■^. Skull like that of S. aureogas- 
ter. Five adult skulls from type locality average : basal length 50.2 ; 
palatal length 26.5 ; interorbital breadth 19.4; zygomatic breadth 35,1 ; 
length of upper molar series 11.8. 

General notes. — This subspecies seems to be peculiar to the Vol- 
cano of Popocatepetl, and probably Iztaccihuatl immediately adjacent. 
One specimen came from near timberline on the north slope of Popo- 
catepetl, the others from Tochimilco on the southeast slope, and Tetela 
del Volcan on the south slope. 

Specimens examined. — Seven : from Tochimilco, Puebla ; Mt. Po- 
pocatepetl, Mexico; and Tetela del Volcan, Morelos. 



58 NELSON 

SCIURUS COLLI^I Richardson. Collie's Squirrel. 

Sciuriis collicei Bachman, Proc. Zool. Soc. London, p. 95, 1838 (nomen 

nudum) ; Richardson, *Voy. of H. M. S. Blossom, Zool., pp. 8-9. pi. 

I, 1839; Bachman, Charlesworth's Mag. Nat. Hist., iii, p. 334, July, 

1839; AuD. & Bach., Quad. N. Am., in, pp. 21-23, pl- civ, 1851 ; 

Allen, Mon. N. Am. Rodentia, pp. 738-740, 1877 (part : specimens 

from San Bias, Mexico). 
Macroxus collicei Gray, Ann. & Mag. Nat. Hist., 3d ser. , xx, pp. 421-422, 

1867 (part : var. 3, Mexico). 
Scitirus hypopyrrhus Alston, Proc. Zool. Soc. London, 1878, pp. 662-664 

(part); Allen, Bull. U. S. Geol. Survey Terr., iv, pp. 881-882, 1878 

(part). 

Type locality — San Bias, Tepic, Mexico. Type in British Museum. 

Distribution. — Arid tropical lowlands and lower slopes of adjacent 
mountains from northern border qjf Tepic south to Bay of Banderas 
(below 2500 feet). 

Characters. — Body large and slender ; upperparts dull yellowish 
gray or dark grayish ; legs and feet grayer ; underparts white. Pelage 
rather thin; hair on back harsh; under fur long and thin; tail long and 
rather full. Teats : p. j- a. |^ i. \. 

Color. — Top of nose iron gray ; rest of upperparts and base of tail 
all around nearly uniform dull yellowish gray or brownish gray shaded 
with black, darkest on crown ; lower border of flanks and sides of 
shoulders rather grayer than back ; outside of legs distinctly grayer 
than back ; feet usually paler or more whitish than legs ; side of head 
dull grayish ; ring around eye paler or more whitish ; ears usually 
somewhat yellower or browner than crown, with basal patch of dingy 
whitish or yellowish white ; underparts white, sometimes pure and 
sometimes darkened by the plumbeous under fur showing through ; 
tail above black, washed with white ; below, with broad median area 
dark grizzled black and yellowish gray, or black, dull gray and yel- 
lowish brown, with narrow indistinct border of black, edged with 
white. Hairs of back black, with rather narrow subterminal or me- 
dian ring varying from pale buffy to brownish %xa.y. 

Variation. — The variation in the San Bias series is small and 
confined mainly to the intensity of the yellowish or buffy of the 
back ; some specimens have the feet and toes whiter than others and 
are grayer on the flanks. Some spring and summer specimens have 
a curious scorched, rusty brown color on the back, as if burned by 
the sun. 

Measurements. — Average of five adults from type locality: total 
length 506.4; tail vertebrae 264.6 ; hind foot 65. 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 59 

Cranial characters. — Premolars \. Skull similar to that of S. 
aureogaster^ but averaging smaller ; jugal slenderer ; upper molar series 
a little narrower and lighter. Four adult skulls from the type locality 
average: basal length 49 ; palatal length 25.6; interorbital breadth 
18.4; zygomatic breadth 32.6; length of upper molar series 11. 

General fiotes. — Specimens from Ixtapa and Las Palmas near the 
Bay of Banderas are intermediate between the San Bias Squirrel and 
S. c. nuchalis. Specimens from Acaponeta near the northern border 
of Tepic are yellower than those from San Bias, thus inclining toward 
the yellow backed S. sinaloensis of Mazatlan. The latter may prove 
a subspecies of collicvi notwithstanding its striking difference in gen- 
eral appearance. 

This species was named in honor of Dr. C. Collie, Surgeon of 
H.Al.S. ' Blossom,' who collected the type during the ship's visit to 
San Bias in the winter of 182S. 

Specimens examined. — Twenty-four: from San Bias, Santiago, 
and Acaponeta, Tepic. 

SCIURUS COLLI^I NUCHALIS subsp. nov. 
Manzanillo Squirrel. 

Type from Manzanillo, Colima, Mexico. Type no. ffff| $ ad., 
U. S. Nat. Museum, Biological Survey Collection. Collected Feb. 
2, 1892, by E. W. Nelson. 

Distribution.— Kx\(k tropical lowlands from the border of Michoa- 
can north along the coast to the Bay of Banderas, Jalisco, and inland 
to the more heavily wooded mountains near San Sebastian, Jalisco 

(below 3000 feet) . 

Characters.— Vf\^&x% from true collicei'm its rusty rufous ears, buffy 
yellow suffusion on nape and shoulders and heavy wash of black on 
lumbar area and rump. Pelage rather thin ; hairs of back coarse, 
stiff and shining : Teats : p. i a. | i. \. 

Description of /y/d?.— Winter, pelage: Upperparts, including 
crown and base of tail, buffy yellowish or yellowish gray, grizzled 
with black on crown and nape and heavily washed over lumbar re- 
gion and rump with shining black ; the yellow more rusty on nape 
and more buffy posteriorly ; flanks paler than back ; ears rusty rufous, 
with small basal patches of rusty or rusty whitish ; sides of nose and 
cheeks dingy yellowish brown; ring around eye paler yellowish; feet 
and outside of legs iron gray, with wash of gray on fore shoulders; 
underparts white, tail, above black rather thinly washed with white; 



6o NELSON 

below at base, grizzled brownish gray, rest of lower surface with a 
broad median band of grizzled rusty yellowish, broadly bordered with 
black and narrowly edged with white. Hair on back black with broad 
median ring of rusty or buffy yellowish. 

Varlatiofi. — Two of the Manzanillo specimens resemble the type 
and are very different from typical collicei. Three others are grayer 
than the type, or less strongly shaded with yellowish on back, but may 
be distinguished from collicei by the rusty ears, more yellowish suf- 
fusion on nuchal area, and heavier wash of black on rump. On three 
of the specimens the median line on lower side of tail is grizzled yel- 
lowish rusty ; on two others it is grizzled gray with a yellowish suf- 
fusion. Specimens from Ixtapa, Las Palmas, Mascota, and San 
Sebastian are intermediate but are more like nuchalis than like true 
collicei. Compared with typical collicei all of the twelve specimens 
from these localities have the ears more yellowish or rusty ; the nuchal 
area yellower than rest of back; the crown, lumbar region and rump 
more heavily washed with black; the median line on lower surface of 
tail grizzled rusty rufous on two specimens, and suffused with a paler 
shade of same on a number of others; pelage coarser and harsher, 
with grizzling on back consequently coarser. 

Measurements. — Average of five adults from type locality : total 
length 530; tail vertebrae 274.8; hind foot 68.4. 

Cranial characters. — Premolars \. Skull similar to that of typical 
collicei but larger, with proportionately larger audital bullae and rather 
broader, heavier jugals. Five adult skulls from the type locality aver- 
age : basal length 53.3; palatal length 27.6; interorbital breadth 
206; zygomatic breadth 35.9; length of upper molar series 11. 4. 

General notes. — This form is characterized mainly by the increased 
rustiness on the head, body, and under side of tail. There is a pro- 
gressive increase in the amount of this color southward from San Bias 
to Manzanillo. 

Specimens exa77tined. — Seventeen: 5 from Manzanillo, Colima; 13 
(all intermediate) from San Sebastian, Mascota, Las Palmas and 
Ixtapa, Jalisco. 

SCIURUS SINALOENSIS sp. uov. Sinaloa Squirrel. 

Type from Mazatlan, Sinaloa, Mexico, no. 13753, $ ad., Ameri- 
can Museum of Natural History, N. Y. Collected Jan. 27, 1897, by 
P. O. Simons. 

Distribution. — iVrid tropical parts of southern and central Sinaloa 
(below 2500 feet) . 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 6l 

Characters. — Crown, nape, and middle of back pale rusty yellow- 
ish ; flanks, legs, and feet whitish. Tail long, bushy; ears thinly 
haired ; pelage rather full and soft ; under fur long. Teats : p. \ a. | 

Color. — Winter pelage : Top of nose gray, shading on fore crown 
into grizzled yellowish gray, rest of crown, nape, middle of shoulders 
and rump pale rust}- yellow slightly grizzled with black ; sides of neck, 
shoulders, costal area, lower flanks, legs and feet grayish white, palest 
on feet; sides of nose and ring around eye dingy gray; cheeks pale 
yellowish brown ; ears dull rusty yellow with small basal patch of 
same; underparts white; tail above brownish yellow, lightly grizzled 
with black and heavily washed with white ; below, a broad median 
area brownish yellow (thinly grizzled with black and lightly washed 
with white) narrowly bordered with black and edged with white. 
Hairs on back black with sub-basal and subterminal rings of rusty. 

Variation. — Specimens of this squirrel from extreme southern 
Sinaloa are a little darker than the type. 

Meas?crements of type. — Total length 524; tail vertebrae 255; hind 
foot 62. 

Cranial characters. — Premolars \. Skull larger and more mas- 
sive than in true collicei\ rostrum decidedly heavier than in collicei ox 
truei^ and heavier even than in aureogaster\ nasals bi"oader and 
more expanded anteriorly. The skull of the type measures : basal 
length 53 ; palatal length 26.3 ; interorbital breadth 20 ; zygomatic 
breadth 34; length of upper molar series 11. 

General notes. — This fine species belongs to the group of which 
S. collicBi^ S. c. nuchalis., and 6". truei are the other members. It is 
the most divergent of all and its rusty yellow back and hoary white 
sides and tail render it easily recognizable. Specimens from near 
Rosario, in extreme southern Sinaloa, are darker than those from 
Mazatlan, and it is possible, notwithstanding its wide difference, that 
sifialoensis may eventually prove to be a subspecies of collicei. 

Specimens exainined. — Four : from Mazatlan, Tatamales, and 
Plomosas, Sinaloa. 

SCIURUS TRUEI sp. nov. Sonora Squirrel. 

Type from Camoa, Rio Mayo, Sonora, Mexico. No. 96229 $ ad. 
U. S. Nat. Museum, Biological Survey Collection. Collected Jan- 
uary 20, 1S99, by E. A. Goldman. 

Distribution. — Scrubby forests of Arid Lower Sonoran zone in 
southwestern Sonora and northern Sinaloa, Mexico. 



62 NELSON 

Characters. — Upperparts of head and body dark yellowish ; outside 
of legs and feet dark gray, in strong contrast to back ; ears behind, 
rusty ; underparts white ; tail slender ; ears thickly haired and sparsely 
tufted; pelage thick and soft; under fur long. Teats: p. \ a. |- i. \. 
'Color. — Winter pelage : Top of nose gray, rest of upperparts, in- 
cluding sides of neck and flanks, nearly uniform dark yellowish, griz- 
zled with black; outside of legs and feet dark gray, slightly paler on 
toes ; ring around eye whitish ; sides of head dingy yellowish gray ; 
ears bordered anteriorly with grayish; behind, including small basal 
patch, rusty ; underparts white ; tail at base like back but washed with 
grayish white below; rest of tail above, grizzled black and dark yel- 
lowish, thinly washed with white; below, mainly dark yellowish, 
grizzled with black, an indistinct narrow black border and thin white 
edge. Hairs on back black, with sub-basal and subterminal rings of 
dark yellowish. 

Variation. — The principal variation in the specimens examined is 
a difference of intensity in the rusty of the ears. 

Measurements. — Average of four adults from type locality : total 
length 487.5 ; tail vertebras 247.5 ' ^ind foot 66.7. 

Cranial characters. — Premolars \. Skull markedly different from 
that of typical collicei. It is proportionately broader with brain case 
more flattened, interorbital area broader; rostrum shorter and heavier; 
nasals shorter and much more deeply emarginate posteriorly ; jugal 
much broader (exceptionally broad) and expanded vertically ; audital 
bullae larger and scarcely depressed on inner anterior border. Four 
adult skulls from type locality average: basal length 47-7' palatal 
length 24.3; interorbital breadth 1S.3; zygomatic breadth 33.2; 
length of upper molar series 1 1 . 

General notes. — Sciurus truei is most nearly related to S. collicei 
from which it may be distinguished by its uniformly dark yellowish 
back, slenderer tail, and mai-ked skull characters. Mr. Goldman 
found it inhabiting the fringe of trees along the Rio Mayo and adja- 
cent foothills, and heard of it in the foothills near Alamos, Sonora, 
close to the border of Sinaloa, so there is no doubt of its occurrence 
also in the northern part of this State. It is named in honor of Mr. 
F. W. True, Executive Curator, U. S. National Museum. 

Specimens examined. — Four : all from type locality. 

SCIURUS SOCIALIS Wagner. Tehuantepec Squirrel. 

Scitirus socialis Wagner, Abhandl. math.-phys. CI. K. bayerisch. Akad. 
Wiss. Munchen, 11, pp. 501, 504-507, pi. v, 1837 ; Suppfement Schreber's 
Saugthiere, iii, pp. 170-171, 1843; Gray, Ann. & Mag. Nat. Hist., 3d 
ser., XX, p. 428, 1867. 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 63 

Sciurus variegatus Alston, Proc. Zool. Soc. London, 1878, pp. 660-662 
(part); Biol. Cent. -Am., Mamm., pp. 127-128, 1880 (part: specimens 
from Tehuantepec); Sumichrast, La Naturaleza, v, p. 324, 1882 (part : 
specimens from southern part of Isthmus of Tehuantepec and Chiapas 
— not S. variegatus ErxL, 1777). 
Sciurus aurcigaster h\.\.YM, Mon. N. Am. Rodentia, pp. 750-753. 1877 (part: 

specimens from Tehuantepec and Santa Efigenia, Oaxaca). 
Sciurus leucops Allen. Mon. N. Am. Rodentia, pp. 753-756 (part : speci- 
mens from Tehuantepec). 
Type locality. — Vicinity of Tehuantepec City, Oaxaca, Mexico. 
Type in Berlin Museum. 

Distribution. — Arid tropical lowland forests along the Pacific 
coast from Puerto Angel, Oaxaca, south to Tonala and Tuxtla, 
Chiapas, Mexico, and up the river valley to Nenton, Guatemala 
(below 3000 feet). 

Characters. — Nape patch usually well defined, rusty rufous; back 
dingy whitish gray overlying yellowish or rusty ; underparts varying 
from white or buffy to bright ferruginous. Pelage thin, hairs of 
back coarse and stiff ; under fur short ; tail long and narrow. Teats : 
p. \ a. f i. f 

Co/or.— Nose and fore part of crown grizzled iron gray; nape patch 
rusty rufous slightly washed with black ; rest of upperparts whitish, 
rather coarsely grizzled with black, and shaded with underlying yel- 
lowish or rusty rufous ; rump patch usually obsolete but sometimes 
more distinctly rusty rufous than surrounding area ; feet like back ; 
ears grizzled gray and rufous, with basal patch white ; extension of nape 
patch around bases of ears, and over cheeks, including eyes, paler and 
more yellowish brown than main area ; ring around eye dingy fulvous ; 
sides of nose and cheeks below eyes dingy grayish white; underparts 
varying from pure white to pale buffy and bright rufous. Tail all 
around at base like rump; rest of tail, above black heavily washed 
with white ; below, median area varying from pale fulvous gray (in 
worn fur) to rich orange — or dark rufous (in good fur), bordered by 
narrow band of black and edged with white. Hairs on back black, 
narrowly tipped with white and mixed with others having broad sub- 
terminal rings of rusty rufous; or in some specimens with white tips 
and broader sub-basal rufous rings 

Variation.— Sciurus socialis is a variable species, characterized by 
general hoariness of back with pale rusty under color showing through, 
and rusty nuchal patch. The color of upperparts varies according to 
the proportionate amount of grayish white and yellowish rufous ; 
sometimes the back is hoary whitish and sometimes the white is re- 
stricted and the underlying reddish or rusty becomes prominent. In 
Proc. Wash. Acad. Sci., May, 1899. 



64 NELSON 

some specimens the nape patch is only slightly marked or entirely re- 
placed by the general whitish color; it is absent in a few specimens 
from near Tehuantepec, and becomes more and more obsolete to the 
south. Our large series, representing both summerandwinterspecimens, 
shows great variation in color of underparts. Midsummer specimens 
with few exceptions vary from pale to deep reddish buff ; the under 
side of tail along median line is usually paler (buffy gray, or yellow- 
ish rufous), and the ear patches are absent or very small. Specimens 
taken in winter, and up to close of dry season in May or June (with 
half a dozen exceptions), are rich rufous below. 

A young female from Huilotepec (May 8) is dingy gray below with 
the buff restricted to axillary and inguinal regions, the middle of the 
back rather darker and more rusty and the sides grayer, in greater con- 
trast with the back than usual. 

An adult female from Tonala in summer pelage differs from all the 
others in having the entire back strongly suffused with light rusty red, 
thinly grizzled with grayish white ; underparts dingy yellowish white 
faintly and minutely grizzled with black ; lower surface of tail grizzled 
dull orange buffy and black, edged with white. Specimens on which 
rufous ringed hairs predominate on the back are suffused with rufous. 
In the series from Puerto Angel north of Tehuantepec City the back 
is much paler or more grayish white, the nuchal patches darker, and 
underparts deeper rufous than in typical socialise but in one case the 
back is uniform grayish white with no sign of a nuchal patch. In the 
series from the vicinity of Tonala south of Tehuantepec the nuchal 
patch is less strongly marked and usually absent; the subterminal ru- 
fous on the back is much more conspicuous, often showing through as 
a strong yellowish rusty suffusion grizzled with white and black ; and 
the underparts vary from pale buffy whitish to dull ferruginous. 

Measurements . — Average of five adults from type locality : total 
length 524.4; tail vertebrae 271.4; hind foot 66.6. 

Cranial characters. — Premolars \. Skull very similar to that of 
S. aureogaster. Five adult specimens from the type locality aver- 
age : basal length 51. 8; palatal length 26.9; interorbital breadth 18. i ; 
zygomatic breadth 33.9; length of upper molar series 11.3. 

General notes. — This species was described from an immature 
specimen taken by the botanical collector Karwinski, who reported 
that it frequented the forest on the southern coast of the Isthmus of 
Tehuantepec in droves. The idea of its gregarious habits, suggesting 
Wagner's name, must have come from seeing it during the mating 
season, when a number are often found together, as in the case of other 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 65 

squirrels. It frequents low scrubby forests and raids cornfields when 
the ears are maturing. 

Specimens examined. — Fifty-four : from Huilotepec (near Tehuan- 
tepec City), Tequisistlan, Colotepec, Puerto Angel, Santa Efigenia, 
Oaxaca ; Calera, Tonala, Tuxtla, Chiapas ; Nenton, Guatemala. 

SCIURUS SOCIALIS COCOS Nelson. Acapulco Squirrel. 

Sciurus aztreogastcr I. Geoffrov, Voy. de la Venus, Zoology, Atlas, pi. 10, 
1846; text, pp. 156-163, 1855 (specimen with white under surface figured 
in pi. 10 of Atlas). Not S aureogaster F. Cuvier, 1839. 

Sciurus socialis cocos NELSON, Proc. Biol. Soc. Washington, xii, pp. 155-156, 
June 3, 1898. 

Type locality. — Acapulco, Guerrero, Mexico. Type no. 70644 
U. S. National Museum, Biological Survey Collection. 

Distribution. — Arid tropical lowlands of the Pacific coast from 
Acapulco, Guerrero, south to Jamiltepec, Oaxaca (below 1500 ft.). 

Characters. — Nape and rump patches distinct, dark rufous brown ; 
back and feet grayish white ; underparts white, buffy, or ferruginous. 
Pelage thin ; hairs on back coarse and stiff ; under fur thin and short. 
Tail long, narrow, and heavily washed with white. Teats i a. |- i. \. 

Color. — Nape and rump patches varying from rusty rufous to deep 
chestnut rufous lightly washed with black; anterior extension of nape 
patch along sides of head enclosing bases of ears and eyes, usually 
rather paler or yellower; ears like nape; top of nose and fore crown 
pale iron gray ; rest of upperparts, including outside of legs and feet, 
grayish white — latter sometimes creamy white; underparts varying 
from pure white to pale creamy buff, rufous buffy or rich dark fer- 
ruginous ; tail above black, heavily washed with white, with rufous 
basal color sometimes showing through ; tail below, with median area 
varying from rufous buffy to rich dark ferruginous, bordered with black 
and edged with white, the white extending also over all of under sur- 
face as an overlying wash. Hairs of back black, with long white 
tips, usually intermixed with others having broad rusty sub-basal rings. 

Variation. — In the series of 33 specimens, all but seven fall within 
the limits of variation already given. The exceptions are described 
below. An adult female from Acapulco (Jan. 10) has the usual dark 
rufous nape and rump patches, the former extending over ears and 
down to eyes ; top of nose and front part of crown clear iron gray ; rest 
of upperparts, including feet and legs white, with a reddish suffusion 
along back; underparts pale creamy buff; tail above black heavily 
washed with white; underside of tail obscurely black and rufous heav- 



dd NELSON 

ily overlaid with white. A male taken at same place (Jan. 19) is 
similar but the white on upper surface is duller and the underparts rich 
buff. 

Another male taken at Acapulco (Jan. 10) has the nape patch even 
richer or darker rufous than usual ; top of nose and fore part of crown 
clear iron gray ; rest of upperparts dingy rusty red, grizzled with 
grayish white ; feet and outside of thighs whiter ; underparts bright 
ferruginous, palest on throat and breast ; tail as usual heavily washed 
with white. 

Two males from Acapulco (Jan. 11) are in a curious melanistic 
condition : One has the nose and fore part of crown black, sparsely 
grizzled with white, the nape and rump patches very rich dark rufous 
washed with black, and the intermediate area along the back black, 
finely grizzled with dark rusty; sides of head, neck and body black, 
overlaid with fine grizzling of dark fulvous and dingy rufous ; feet 
glossy black; tail black, thinly washed with white above and below, 
with dark rusty rings near bases of hairs ; underparts smoky black 
washed with fulvous brown and dull rusty. The other melanistic 
specimen has the top of head as in the last ; the nape and rump patches 
black, the rest of upper parts dull rusty brown grizzled with black 
and more sparsely with white ; chin dark gray; throat grizzled rufous; 
rest of underparts dark reddish brown becoming darker posteriorly ; 
tail above black heavily overlaid with white; below black, heavily 
bordered with white. 

A female taken at Llano Grande, Oaxaca (Feb. 18) has the nose 
and fore part of crown black, grizzled with gray ; nape and rump 
patches dingy rusty, heavily washed with black ; rest of back grizzled 
reddish brown and black, shading into dark yellowish brown on sides ; 
feet grizzled black and grayish brown; toes black; underparts dark 
dingy buff; tail above black, washed with white; below, median band 
buffy yellow with broad border of black, edged with white. 

Measurements. — Average of 5 adults from type locality : total 
length 518.2 ; tail vertebrae 268; hind foot 66. 

Cranial characters. — Premolars \. Skull very similar to that of 
S. socialis but somewhat shorter; broader interorbitally ; upper molar 
series slightly shorter. Five adult skulls from the type locality aver- 
age : basal length 50. 8; palatal length 26.5; interorbital breadth 19.3; 
zygomatic breadth 33.7; length of upper molar series 10.6. 

General notes. — In the Zoology of the Voyage of the Venus, 
under the name 6". aureogaster., is a good figure of a white bellied 
specimen of this species, which probably came from Acapulco. On 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 67 

the way south from that port we took the last typical specimen of S. s. 
cocos at Jamiltepec, Oaxaca ; the series taken beyond, at Puerto 
Angel, is intermediate between true socialis and cocos. We found 
these squirrels frequenting cocoanut groves near Acapulco and feeding 
upon the nuts. It is the only squirrel we saw doing this although 
cocoanut trees are common in the ranges of various other species. 
The name of the subspecies was suggested by this peculiar habit. 

Specimens exa?nhzed. — Thirty-three : from Acapulco, Aguacatillo, 
San Marcos, and Ometepec, Guerrero ; Pinotepa, Llano Grande and 
Jamiltepec, Oaxaca. 



SCIURUS GRISEOFLAVUS (Gray) Guatemala Squirrel. 

Sciuriis ludovicianits Tomes, Proc. Zool. Soc. London, p. 281, 1861 (from 
Duenas, Guatemala. Not S. litdovicianus Custis, 1806). 

Macro xtis griseoflavus Gray, Ann. & Mag. Nat. Hist., 3d ser. , xx, p. 427, 
1867. 

Sciurus aurcigasfer kiA.Y.'^, Mon. N. Am. Rodentia, pp. 750-753, 1877 (part : 
No. 1 1 56 from Guatemala). 

Sciurus griseoflavus Alston, Proc. Zool. Soc. London, p. 660, 1878 ; Biol. 
Cent. -Am., Mamm., pp. 126-127, 1880; Allen, Bull. U. S. Geol. Sur- 
vey Terr., iv, pp. 880-881, 1878. 

Sciurus affinis (Reinhardt, MS. in) Alston, Proc. Zool. Soc. London, p. 
660, 1878 (nomen nudum). 

Type locality. — ' Guatemala.' (Specimens from near Duenas are 
typical). 

Distribution. — Oak and pine forests of the Transition and Boreal 
zones in central and northwestern Guatemala and adjacent high 
mountains in southeastern Chiapas, Mexico. 

Characters. — Size large and heavy. Color of upper parts grizzled 
yellowish brown, thinly washed with gray (especially in winter) ; 
belly fulvous brown or rusty rufous. Pelage full and soft ; under 
fur long; tail broad and flat. Teats: p. i a. f i. \. 

Color. — Upperparts, including crown and base of tail, grizzled 
yellowish brown, sometimes thinly washed with grayish white ; out- 
side of legs like flanks ; feet usually grayer, but sometimes grizzled 
yellow and brown, and sometimes dark yellowish brown ; top of nose, 
sides of head, and ears, grayer than crown; an indistinct dingy 
grayish ear patch sometimes present ; chin and throat pale grayish 
fulvous ; rest of underparts varying from dark dull rufous to dingy 
grayish washed with reddish fulvous ; tail above black washed with 
white, with underlying yellowish brown showing through ; below, 
with broad median area grizzled yellowish or rufous brown, bordered 



68 NELSON 

by a narrow black line, and thinly edged with white. Some hairs on 
back entirely black, others black with white tip and either a sub- 
basal ring or basal and median rings of brownish yellow. 

Variation. — The gray wash on the back varies greatly, sometimes 
being entirely absent, especially in specimens from the humid forests 
fronting the Pacific Ocean ; in others it is general over the dorsal sur- 
face, and in others still is confined to a band across the back, leaving 
poorly marked rusty or yellowish brown nuchal and rump patches of 
varying size. In one specimen the nape patch is chestnut brown, the 
middle of back washed with light gray and the rump yellowish brown. 
In winter, the white wash on the back is most conspicuous, and the 
underparts are duller and less strongly ferruginous. (They may be dark 
ferruginous, or dark grizzled grayish washed with fulvous, or pale fer- 
ruginous). The absence of white tips produces the yellowish brown 
nape and rump areas, or wholly yellowish brown backs of specimens 
from the humid forest fronting the Pacific. Such specimens have 
many hairs with subterminal rings of rusty yellow. 

Measurements. — Average of two adults from central Guatemala, 
from dried skins: total length 547.5 ; tail vertebras 270; hind foot 68. 

Cranial characters. — Premolars \. Skull a little longer than that 
of S. aureogaster but otherwise very similar. Four adult skulls from 
southwestern Guatemala average: basal length 51.8 ; palatal length 
27.2; interorbital breadth 19; zygomatic breadth 34.4; length of 
upper molar series 11.4. 

General notes. — A specimen from central Guatemala (No. 61226 
U. S. Nat. Museum) sent to London for comparison with Gray's 
type, was pronounced by Mr. Thomas to closely resemble the two 
cotypes on the dorsal surface but is richer rufous below with less white 
on the tail. These differences fall within the minor individual varia- 
tions. 

Gray gave ' Guatemala' as the type locality for this species, and 
specimens from near Duenas are typical. Specimens from the dense 
humid forests near Guatemala City and thence along the slopes of the 
mountains fronting the Pacific to Pinabete, Chiapas, are darker or 
browner than those from the higher mountains of the interior. Those 
from Calel are a little paler than typical specimens, and those from 
the forest at the Hacienda Chancol are still grayer or nearer the form 
from the mountains of central Chiapas. 

Habits. — We found these squirrels rather common in the dense oak 
forests at about 7000 feet above sea level on the volcano of Santa 
Maria, near Quezaltenango, but owing to the tangled undergrowth and 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 69 

the abundance of parasitic plants on the trees it was difficult to secure 
specimens. Near Calel, and at Hacienda Chancol, they were less 
common among other species of oaks in the more open forest at an 
altitude of 9000 to 10,000 feet, but were very shy, and it required cau- 
tious and long continued hunting to secure a few specimens. 

Spechnens examined. — Twenty-two : from vicinity of Guatemala 
City, Volcano Santa Maria, Calel, Hacienda Chancol, Guatemala; 
and Pinabete, Chiapas. 

SCIURUS GRISEOFLAVUS CHIAPENSIS subsp. nov. 
Chiapas Squirrel. 

Type from San Cristobal, Chiapas, Mexico. No. 75957, $ ad., 
U. S. Nat. Mus., Biological Survey Collection. Collected Sept. 22, 
1895, by E. W. Nelson and E. A. Goldman. 

Distribution. — Pine and oak foreslsof Transition and Boreal zones 
in mountains of central Chiapas (alt. 7500-9500 feet). 

Characters. — Similar to true 6^. griseojlaviis but differing in the 
decidedly grayer upperparts ; paler, often nearly white, feet, and usu- 
ally more vivid ferruginous underparts. Pelage full and rather soft ; 
under fur long and dense ; tail broad and full. Teats : p. \ a. | i. \. 

Color. — Winter pelage : Upperparts, including outside of legs, top 
of nose, and base of tail, dark grizzled gray (rather darker on top of 
head), interspersed with many scattered hairs having median rings of 
reddish buffy ; ears dingy whitish gray with small whitish basal 
patches ; feet grayish white, the toes often nearly white ; narrow ring 
around eyes pale fulvous, confluent with a darker area of fulvous 
brown extending back along sides of head to base of ears; sides of 
nose, lower cheeks, chin and throat, pale grayish ; underparts usually 
rusty rufous, brighter than in true griseoflaviis ; tail at base all around 
like back ; above, black heavily washed with white ; below, usually 
with broad median area of yellowish, yellowish brown or rusty rufous, 
black border and well marked white edge. Hairs on back black, 
tipped rather broadly with white and often with broad median rings of 
reddish buff (most numerous and conspicuous along flanks). 

Variation. — The series at hand shows but little variation in the 
upperparts. In some specimens the crown is darker, and the brown area 
behind the eyes more distinctly marked ; the feet vary from grizzled 
gray to almost white. The greatest variation is in the underparts and 
tail. Eight of the twelve specimens are bright ferruginous below, 
one is dull buffy yellow, one dark grizzled gray heavily washed with 



70 NELSON 

rusty rufous, while the two others are washed with rufous except a 
grizzled gray band about 4 inches broad across the belly. The median 
area on the lower surface of tail is sometimes broad, sometimes merely a 
narrow line (the black border increasing in width as the other de- 
creases) and varies from rusty ferruginous to yellowish brown. 

Measurements. — Average of five adults from type locality : total 
length 506.2 ; tail vertebrae 256; hind foot 68.2 

Cranial characters, — Premolars \. Skull a little shorter than that 
of griseojlavus but scarcely distinguishable from the latter or from 
that of kS. aureogaster. Five adult skulls from the type locality aver- 
age : basal length 50.9; palatal length, 26.6; interorbital breadth 
19. 1 ; zygomatic breadth 34.3 ; length of upper molar series 11.4. 

General notes. — The squirrels taken in the oak forest between 9000 
and 10,000 feet altitude on the mountains at Todos Santos, Guatemala, 
are intermediate between chiapejisis and true griseojiaviis. Those 
taken at Calel, Guatemala, are more yellowish brown and much closer to 
griseojlavus. A specimen from the arid subtropical canyon at Nenton, 
Guatemala (below 3000 feet) , and two others from similar localities near 
Tuxtla, Chiapas, seem to indicate a direct gradation, in this intermediate 
region, between S. griseojlavus chiapensis and S. socialis. Unfortu- 
nately our series from intermediate points is too limited to satisfactorily 
decide this point. Surprising as it may appear, the differences be- 
tween griseojlavus chiapensis and socialis are not greater than those 
between the latter and S. socialis cocos. 

Habits. — The Chiapas squirrel feeds upon both acorns and pine 
seeds, moving from one part of the forest to another with the season. 

Specimens examined. — Twelve : all from the type locality. 

SCIURUS YUCATANENSIS Allen. Yucatan Squirrel. 

Sciurus carolifiensis var. yucatanensis Allen, Mon. N. Am. Rodentia, pp. 

705-706, Aug., 1877 ; Bull. U. S. Geo). Survey; Terr., iv, p. 879, 1878. 
Sciurus caroline-nsis Alston, Proc. Zool. Soc. London, 1878, pp. 658-659 ; 

Biol. Cent. -Am., Mamm., pp. 124-125, June, 1880 (part: specimens 

from Yucatan). 
Sciurus yucatanensis Allen, Bull. Am. Mus. Nat. Hist., N. Y., ix, pp. 5-7, 

1897. 

Type locality. — Merida, Yucatan, Mexico. Cotypes nos. 8';o2- 
8503. U. S. National Museum. 

Distribution. — Arid tropical forests of peninsula of Yucatan. 

Characters. — Back dingy, coarsely grizzled gray; belly white; 
l^elage coarse and harsh but not bristly ; thin ear tufts sometimes pre- 
sent, yellowish white ; tail rather full. 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 7 1 

Color. — Upperparts, including feet, rather coarsely grizzled black 
and gray (sometimes suffused with yellowish), more yellowish along 
middle of back and paler gray on sides of nose, body, and feet ; ring 
around eye dingy whitish ; ears sometimes dark gray and sometimes 
with distinct dingy white basal patch and small dull yellowish white 
tuft at tip 8 or 9 mm. long; underparts varying from white to pale 
grizzled gray. Tail at base similar to back; rest of tail above black, 
heavily washed with white ; below, with median area coarsely grizzled 
black and gray, or dull, pale fulvous, bordered by black and edged with 
white. Hairs on back black, with broad median ring of w^hite or 
yellowish. 

Varlatioft. — The small series examined does not show much sea- 
sonal difference, but the presence of ear patches and small tufts in two 
specimens ( $ and 9 ) and their absence in three others indicate the 
probable existence of certain marked differences of this kind. One 
specimen taken at Chichenitza (Mar. 7) is mainly iron gray with slight 
trace of yellow on the back ; the underparts are w^hitish finely grizzled 
with black. Another specimen taken at the same locality (Mar. iS) 
has a strong yellowish shade on the upperparts, and the chin, neck, 
breast, and middle of belly are nearly pure white, the underparts being 
grizzled with black only along border of flanks. 

Measurements. — Average of two adults from Chichen-Itza : total 
length 451 ; tail vertebne 232 ; hind foot 55. 

Cranial characters. — Premolars f . Skull very similar in general 
outline to that of typical S. aureogaster but much smaller, with pro- 
portionately longer nasals and larger audital bullse ; nasals rounded in 
front as in aureogaster. The single skull at hand shows no approach 
to the massive rostrum and broad flattened nasals of the thotnasi 
group. It measures: basal length 45 ; palatal length 23; interorbital 
breadth 16.3; zygomatic breadth 19; length of upper molar series 9.5. 

General notes. — Sciiiriis yucatanensis is at once separable from 
6". carolinensis and its races, and from S. alleni., by the much coarser 
grizzling on the back, and the stiffer, harsher pelage in addition to the 
cranial characters. It is a strongly marked species, the presence of 
whitish ear tufts in certain pelages separating it from the other Mexi- 
can and Central American squirrels of the subgenus Echinosciurus. 

Specimens examined. — Five : from Merida and Chichen-Itza, Yuca- 
tan. 

SCIURUS THOMASI sp. nov. Costa Rica Squirrel. 

Sciurus boot/lice Allen, Mon. N. Am. Rodentia, pp. 741-746, 1877 (part: 
specimens from eastern Costa Rica. — Not S. boothicE Gray, 1842). 



72 NELSON 

Scinrits hypopyj-rJuis Alston, Proc. Zool. Soc. London, pp. 662-664, 1878 
(part); Allen, Bull. U. S. Geol. Survey Terr., iv, pp. 881-882, 1878; 
(part); Alston, Biol. Cent. -Am., Mamm., pp. 123-131, 1880 (part: 
specimens from interior of Costa Rica) ; Allen, Bull. Am. Mus. Nat. 
Hist., N. Y., Ill, p. 206, 1891 ; Bull. Am. Mus. Nat. Hist., N. Y., ix, p. 35, 
1897 ; Alfaro, Mamiferos de Costa Rica, pp. 30-31, 1897 (part : speci- 
mens from eastern Costa Rica), 

Type from Talamanca, Costa Rica. No. ^Ifff U. S. National 
Museum. Collected by Wm. Gabb. 

Distribution. — Humid tropical forests of eastern Costa Rica. 

Characters. — Entire upperparts black with underlying dark yel- 
lowish or ferruginous brown shining through ; underparts rich deep 
ferruginous ; pelage thin ; hair on back coarse, stiff, and glossy ; under 
fur short and thin ; tail long and nan-ow. 

Color. — Upperparts, including crown, base of tail, sides of neck, 
and outside of legs, nearly uniform glossy black with yellowish or 
ferruginous brown of underlying color shining through ; top of nose, 
chin, and sides of head dingy grayish brown ; ears blackish with thin 
tufts of black hairs at tips and conspicuous basal patches of ferrugin- 
ous; feet varying from black to grizzled ferruginous brown, latter 
color sometimes extending as a wash over outside of legs; entire un- 
derparts rich ferruginous, sometimes varied with irregular white areas ; 
tail above black, thinly washed with white ; below with median area 
black grizzled with ferruginous or yellowish brown, narrowly bordered 
with black and thinly edged with white. Hairs on back shining black 
with broad median ring of rusty buffy or rufous brown. 

Variation. — The underlying color of the back and the ear patches 
vary from yellowish brown to rich ferruginous. The darkest, most 
intensely colored specimen is from Santa Clara and has the median 
rings on hairs of back nearly as deep ferruginous as the underparts. 

Measurements. — Average of four adults from eastern Costa Rica 
(from dry skins): total length 517.5; tail vertebrge 246.5; hind 
foot 62.2. 

Cranial characters. — Premolars \. Skull (pi. II, fig. 6) even 
broader and stouter than that of S. boothice belti ; rostrum much 
broader and heavier; interorbital breadth much greater; occiput 
broader. The type skull measures : basal length 50 ; palatal length 
26.2; interorbital breadth 22; zygomatic breadth 35.5; length of 
upper molar series 11. 5* 

General notes. — This species seems to occupy the more humid 
area of eastern Costa Rica, ranging inland to the border of the more 
arid western slope where it meets S. adolphci dorsalis. It may be 



SQLTIRRELS OF MEXICO AND CENTRAL AMERICA 73 

readily distinguished from the latter by the ferruginous ear patches and 
blackish dorsal surface, the top of head not being paler than back. 
Although specimens of both S. thomasi and S. dorsalis are before 
me from the same locality, La Carpintera, where their ranges meet, 
there are no intergrades. I take great pleasure in naming this hand- 
some species in honor of Mr. Oldfield Thomas, Curator of Mammals 
in the British Museum. 

Specimens examined. — Five : from Talamanca, La Carpintera and 
Santa Clara, Costa Rica. 

SCIURUS ADOLPHEI (Lesson). Nicaragua Squirrel. 

Macroxus adolphei Lesson, Rev. Zool., v, p. 130, 1842 (nomen nudum); 

Nouv. Tabl. Regne Animal, Mamm., pp. 11 2-1 13, 1842 ; Gray, Ann. 

& Mag. Nat. Hist., 3d sen, xx, p. 433. 1867. 
Sciurus boothicE Allen, Mon. N. Am. Rodentia, pp. 741-746, 1877 (part: 

Nicaragua). 
Sciurus hypopvrr hies Ai^STO^i, Proc. Zool. See. London, 1878, pp. 662-664; 

Allen, i3ull. U. S. Geol. Survey Terr., iv, pp. 881-882, 1878 (part); 

Alston, Biol. Cent. -Am., Mamm., pp. 128-131, 1880 (part). 

Type locality. —R.eii\e]o, Nicaragua. Type in Paris Museum. 

Distribution. — Tropical lowlands on west coast of Nicaragua. 

Characters.— Ho^ of head and nape iron gray, paler than back ; 
rest of upperparts and base of tail dark grayish brown ; underparts 
and outside of fore and hind legs reddish chestnut brown, sometimes 
with patches of white. Pelage thin ; hairs of back coarse, stiff, and 
shining ; under fur short. 

Color.— To'g of nose and crown dull iron gray; nape grayish 
brown; rest of back and upper part of thighs darker brown, with a 
shade of grayish, slightly paler on flanks ; sides of nose, cheeks and 
sides of neck grayish brown ; ears like crown and with well marked 
white basal patches; feet dark chestnut grizzled with blackish; fore- 
legs all around (except axiUar area), adjacent part of shoulders, 
lower border of costal area and outer border and inside of thighs 
(except inguinal area) dark reddish chestnut; underparts (except 
white chin, throat, axillar and inguinal region), of same reddish chest- 
nut as legs; tail at base dark grizzled brown; tail above black heavily 
washed with white ; below, with broad median area of rusty brown, a 
narrow black border and white edge. Hairs on back black, with 
broad median ring of dull yeMowish or slightly reddish brown. 

Measurements.— Ad.u\t, No. S495 U. S. Nat. Museum (from dry 
skin) : total length 440; tail vertebra 199 (tail imperfect) ; hmd foot 
65. In the flesh the total length of this species must exceed 500 mm. 



i 



74 NELSON 

General notes. — The type specimen of S. adolphei was collected 
during the voyage of the French ship ' La Pylade ' by the ship's surgeon, 
Adolphe Lesson, in whose honor the species was named. The speci- 
men described above differs from the description of the type only in 
being a little less intensely colored on the back and in having less white 
on the underparts. Lesson mentions another specimen from the same 
locality which had a black dorsal line, grayish sides and flanks, with 
grizzled gray and white on outside of legs. This squirrel appears to 
differ from S. a. dorsalis mainly in its darker colors. 

Specimens exainined. — One : from west coast of Nicaragua. 

SCIURUS ADOLPHEI DORSALIS (Gray). 
Banded-backed Squirrel. 

Sciuriis dorsalis Gray, Proc. Zool. Soc. London, p. 138, 1848 ; Sclater, 

Ibid., 1870, pp. 670-671. 
Sciitrus rigidus Peters, Monatsber. K. Pr. Akad, Wiss., Berlin, 1863, pp. 

652-653. 
Sciurus intermedius Gray, Ann. & Mag. Nat. Hist., 3d ser., xx, p. 421, 1867. 
Macroxus dorsalis Gray, Ann. & Mag. Nat. Hist., 3d ser., xx, pp. 422-423, 

1867 (part). 
Macroxus nicoyana Gray, Ann. & Mag. Nat Hist., 3d ser., xx, p. 423, 1867. 
Macroxus melajiia Gray, Ann. & Mag. Nat. Hist., 3d ser., xx, p. 425, 1867.' 
P Sciurus boothicF A.i.x.r.'^, 'Mon. N.Am. Rodentia, pp. 741-746, 1877 (part : 

specimens from Costa Rica). 
Sciurus JiypopyrrJius Allen, Mon. N. Am. Rodentia, pp. 746-750, 1877 

(part : No. 862S from Costa Rica) ; Alston, Proc. Zool. Soc. London, 

1878, pp. 662-664 (part); Allen, Bull. U. S. Geol. Survey Terr., iv, pp. 

881-882, 187S (part); Alston, Biol. Cent.-Am., Mamm., pp. 128- 

131, 1880 (part); Alfaro, Mamiferos de Costa Rica, pp. 30-31, 1897 

(part : west coast of Costa Rica). 

Typelocality. — Erroneously given as Caracas, Venezuela. (Speci- 
mens from Liberia, Costa Rica, are typical.) Type in British Museum. 

Distribution. — Comparatively arid parts of tropical western Costa 
Rica from near Alajuela (or perhaps even farther south) north to dis- 
trict about Liberia, the peninsula of Nicoya, and perhaps adjacent part 
of Nicaragua. 

Characters. — Colors brighter than in 6". adolpJiei ; top and sides of 
head decidedly paler and grayer than back ; broad area along middle 
of back from nape to base of tail blackish brown or grizzled yellowish 
brown enclosed by band of lighter or paler grayish along sides ; under- 
parts white, buffy yellowish or bright rufous. Tail long and narrow; 

1 This may be a valid species or subspecies but the type was evidently a me- 
lanistic specimen and in the absence of material I refer it here. The type came 
from extreme southern Costa Rica (Point Burica). 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 75 

pelagje thin ; hair on dorsal surface coarse and stiff ; under fur thin. 
Teats: p. \ a. ^ i. \. 

Color. — This subspecies lias several color phases of which the two 
most characteristic are described below. Blackish-backed phase: 
Top and sides of head grizzled gray, paler than back ; back with 
broad band (widening on lumbar region and narrowing thence to 
tail) blackish, blackish brown, or dark yellowish brown, bordered by 
band (half an inch to an inch wide) of whitish or gray, paler than 
dorsal area and separating it from color of underparts ; lower flanks, 
all of legs, feet, and underparts nearly uniform white, buffy, or 
rufous ; cheeks, chin and sides of neck grizzled gray or grayish brown ; 
ears grizzled gray or grayish brown, sometimes bordered with black; 
ear patches white; tail above black, heavily washed with white, 
below, a broad median area varying from dark rufous to rusty orange 
or grayish white, bordered by a black line and edged with white. 

Grizzled-backed phase : Top and sides of head pale gray or 
grayish brown, paler than back; rest of back grizzled grayish brown, 
yellowish brown or blackish brown, darkest on upper half and paler 
or grayer along sides and on legs; sides usually more or less strongly 
mixed with color of underparts; fore feet like underparts or heavily 
washed with same color; hind feet similarly washed but more nearly 
like outside of hind legs ; underparts rusty, bright ferruginous, or 
buffy, sometimes vv^th irregular white patches; ears like top of head; 
ear patches large, white ; sides of head and chin dull grayish or 
grayish brown ; tail above at base like back, rest of upper surface 
black, washed with white ; below with median band of rusty, rufous, 
or yellowish brown bordered by black and edged with white. 

Hairs on middle of back of blackish backed specimens, brownish 
black with scattered white tips ; hairs on flanks of these specimens 
blackish broadly tipped with white or rufous. Hairs on specimens 
with grizzled backs, black with median or subterminal ring of rusty 
buffy, brownish yellow or grayish brown; on flanks similar but usually 
paler and sometimes with whitish tips. 

V^ariations. — This is an extraordinarily variable squirrel. The top 
of head and upper part of flanks are usually paler than the median 
dark dorsal area ; the underparts, lower flanks and outside of legs and 
feet may be white, some shade of buff, or bright rufous ; or the back may 
be grizzled brown, with the same color extending over flanks to outside 
of legs and mixing with the color of the feet. In some cases where 
the last described phase is most marked the head is but little paler 
than back, especially in specimens from vicinity of San Jose and La 



176 NELSON 

Carpintera. At the latter place the range of this subspecies appears 
to join that of 6'. thomasi, but no intergrades have been seen. 

Afeasure?nents. — Average of four adults from northwestern Costa 
Rica (from dry skins) : total length, 510 ; tail vertebrae 24S.5 ; hind 
foot 63.2. . 

Cranial characters. — Premolars \. Skull like that of 6". b. belti^ 
and similar to that of 5". tJiomasi but rather larger with slender ros- 
trum. Two adult skulls from northwestern Costa Rica average : 
Basal length 51.7; palatal length 27.7; interorbital breadth 21.8; zy- 
gomatic breadth 35.2; length of upper molar series 11.7. 

General notes. — In the original description of Sciurus dorsalis 
Gray gave Caracas, Venezuela, as the type locality. Dr. Sclater has 
since stated^ that the type came from Nicaragua, but Mr. Thomas writes 
that he does not know on what authority. Citations of this squirrel 
from Nicaragua are probably referable to true adolphei. A number 
of specimens examined by me from northwestern Costa Rica, especially 
from near Liberia, agree exactly with Gray's description, and one 
(No. 15759 U. S. Nat. Museum, from Liberia, Costa Rica) sent Mr. 
Thomas for comparison was pronounced by him to be absolutely like 
the type. 

The type locality of Gray's Macroxus nicoyana., based on a rufous 
color-phase of 6". a. dorsalis., was given as Nicoya, a town on the 
peninsula of Nicoya, in northwestern Costa Rica. S. rigidus of 
Peters and S. intermedins of Gray are based upon a phase of 
dorsalis in which the head and upper part of flanks are nearly 
as dark as the middle of the back, but the underpai-ts, lower flanks, 
and outside of legs and feet are nearly uniform bright rufous. Mr. 
Thomas has compared a specimen from Alajuela, Costa Rica (No. 
15757 U. S. Nat. Museum) with Gray's type of intermedins in the 
British Museum and pronounces it identical, differing only in slightly 
duller colors. The type of S. rigidus came from San Jose, Costa 
Rica. The type locality of intermedins was given as Guatemala — 
evidently an error, as no squirrel of this style is found in Guatemala, 
while it is common in western Costa Rica. 

Specimens examined. — Twenty : from San Jos^, La Carpintera, 
Alajuela, Bebedero, San Mateo, Liberia and Nicoya, Costa Rica. 

SCIURUS BOOTHIA Gray. Honduras Squirrel. 

Sciurus richardsoni Gray, Ann. & Mag. Nat. Hist., x, p. 264, 1842 (not S. 
richardsoni Bachman, 1838). 

^Proc. Zool. Soc, London, 1870, pp. 670-671. 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 77 

Sciiirns boothicE Gray, List. Spec. Mamm. Brit. Mus., p. 139, 1843 ; Voy. 

H. M. S. 'Sulphur,' Zool., p. 34, pi. 13, fig i, 1863. 
Sciums fuscoz'arit'gatus Sciw^z, Synopsis Mamm., 11, pp. 15-16, 1845. 
Alacroxus boothice Gray, Ann. & Mag. Nat. Hist., 3d sen, xx, p. 424, 1867. 
Sciurits hypopyrrhus Alston, Proc. Zool. Soc. London, pp. 662-664, 1878 

(part); Allen, Bull. U. S. Geol. Survey Terr., iv, pp. 881-882, 1878 

(part); Alston, Biol. Cent. -Am., Mamm., pp. 128-131, 1880 (part: 

specimens from Honduras). 

Type locality. — 'Honduras' (specimens from San Pedro Sula are 
typical). Type in British Museum. 

Distribution. — Humid tropical coast forests of northern Honduras 
and border of Guatemala. 

Characters. — Back dark grayish brown, washed with shining 
black ; belly white ; feet blackish ; ears black edged, with basal patches 
dark rusty ; upper- and imderparts separated by a narrow line of dull 
reddish brown along flanks. Pelage thin ; hairs on back coarse, stiff, 
and shining; under fur short; tail long and narrow. Teats: p. i a. |^ 

Color. — Upperparts, includhig top of nose and base of tail, uniform 
coarsely grizzled dark grayish brown, sometimes faintly suffused with 
reddish ; outside of legs and feet similar, but darker and sometimes al- 
most shining black ; ears bordered with black ; basal patch on back of 
ears dingy rusty ; chin and sides of head dull grayish brown ; entire 
underparts white ; tail at base all around like back ; rest of tail above 
black thinly washed with white; below, median area grizzled dark 
brownish suffused with yellowish or faint rufous, bordered with black, 
and thinly edged with white. Hairs on back black, with broad 
median ring of grayish or buffy brown. 

Variation. — Three specimens from San Pedro Sula and one from 
Truxillo, Honduras (July), vary but little, the uppei-parts being 
washed with black over brownish, the feet black or blackish, grizzled 
with grayish brown or dull reddish brown, the underparts uniformly 
white. 

A half grown specimen in the National Museum labeled ' Guate- 
mala' differs from typical specimens in having the outside of the feet 
and legs black; sides of head and chin finely grizzled dark gray; 
underjDarts finely grizzled grayish brown, and lower surface of tail 
black, grizzled with gray near base. 

Measuretnents. — Average of three adults from San Pedro Sula 
(from dry skins) : total length 534; tail vertebra 355 ; hind foot 63.3. 

Cratiial characters. — Premolars f . The only skull of this species 
at hand from San Pedro Sula is immature, but its proportions appear 
to be the same as those of subspecies belli. 



i 



78 NELSON 

General notes. — Gray first called this species S. richardsoni in 
1842, but finding this name preoccupied by S. richardsoni of Bach- 
man, 1S38, he renamed it S. boothia: in 1843. Overlooking Gray's 
■change, Schinz renamed the species S. fuscovaricgatus in 1845. 
Most recent authors have lumped this squirrel with numerous others 
under the name hypopyrrhus. 

Mr. Oldfield Thomas, to whom a specimen from San Pedro Sula, 
Honduras (No. 19549 $ ad., U. S. National Museum) was sent for 
comparison with Gray's type, writes that they agree absolutely in color. 
Gray gives no definite type locality for this species, but specimens from 
San Pedro Sula are absolutely typical. Mr. Thomas writes that the 
type is less than half grown and that in retiescribing this species in 1867 
(Ann. and Mag, Nat. Hist., 3d. ser., xx, p. 424) Gray mentions, 
not the type, but specimens received by the British Museum from 
Honduras in 1845 which have gray instead of white bellies. S. 
boothice grades into S. b. belti to the south, and it is very probable 
that another subspecies exists in the mountains of interior Honduras. 
I have been unable to learn for whom Gray named this species. 

Specimens examined. — Eight : from San Pedro Sula, Truxillo, and 
Segovia River, Honduras; Guatemala (i specimen without definite 
locality) . 

SCIURUS BOOTHIA BELTI subsp. nov. 
Escondido River Squirrel. 

Type from Escondido River, 50 miles from Bluefields, Nicaragua. 
No. 1^1^^ 9 ad., U. S. Nat. Museum, Biological Survey Collection. 
Collected Nov. 22, 1892, by Chas. W. Richmond. 

Distributio7i. — Humid tropical forests of eastern coast region of 
Nicaragua and north to Segovia River, Honduras. 

Characters. — Differs from S. boothice mainly in having the un- 
derparts uniformly rusty rufous, and feet grizzled with rusty yellow- 
ish. Pelage thin ; hair on back coarse, stiff and shiny ; under fur 
short and thin; tail flat and slender. Teats: p- y a- f !• \- 

Color. — Upperparts including top of nose and base of tail all 
around grizzled grayish brown, more or less heavily washed with 
black ; ears bordered with black, posterior surface and basal patches 
dull rusty; sides of head and chin varying from yellowish brown to 
brownish gray; feet black, grizzled with rusty yellowish ; outside of 
fore and hind legs like flanks but appreciably suffused with 'rusty yel- 
low ; tail above black, thinly washed with white ; below, median area 
varying from grizzled yellowish brown to rusty, with narrow black 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 79 

border and still narrower white edge. Hairs on back, black with a 
broad dull bu£fy or yellowish gray median ring. 

Variation. — The ground color of the back varies from grayish 
brown with a light suffusion of reddish, to clayey brown with an 
overlying wash of shiny black. The rusty suffusion on outside of 
legs is strong in some and light in others. An August specimen is 
practically the same as others taken in November, thus indicating 
little or no seasonal change. One from the Segovia River, Honduras, 
is like those from the type locality, except that the underparts are 
deeper rufous. Another from the same locality has a brownish shade 
in the rufous of underparts, and large irregular pectoral and abdom- 
inal white areas connected by a narrow white median line. A third 
has the vmderparts grizzled rusty brown with a large, irregular 
median white line. These specimens (June and July) have the 
back heavily washed with black and in some respects are intermediate 
between typical boothice and belti. A single melanistic specimen 
from Nicai-agua is the only one seen. 

JSIeasurements. — Average of five adults from type locality: total 
length 513; tail vertebrae 261.6; hind foot 61.7. 

Cranial characters. — Premolars -=-. Skull (pi. II, figs, i and 5) 
generally similar to that of S. aureogaster., but rostrum broader and 
heavier, anterior end of nasals broader and more flattened, interorbital 
width greater, occiput usually broader; the small premolar heavier, 
thus resembling S. tJiomasi. Four adult skulls from the type locality 
average: Basal length 48. 8 ; palatal length 25.5; interorbital breadth 
19.6; zygomatic breadth 33.7 ; length of upper molar series 1 1.4. 

General notes. — This subspecies is named in honor of Thomas 
Belt, the well known author of ' A Naturalist in Nicaragua.' 

Habits. — Dr. Richmond found these squirrels living in the forests 
along the borders of clearings or other openings. 

Specifnens examined. — Eight: from Escondido River, Nicaragua; 
and Segovia River, Honduras. 

SCIURUS VARIEGATOIDES Ogilby. Variegated Squirrel. 

Sciuriis variegatoides Ogilbv, Proc. Zool. Soc. London, 1839, p. 117 ; Ann. 

& Mag. Nat. Hist., v, pp. 62-63, 1840; Wagner, Supplement. Schre- 

ber's Saugthiere, III, pp. 185-186, 1843. 
Macroxiis pyladei Lesson, Rev. Zool., Paris, v, p. 130, April, 1842 (nomen 

nudum); Nouv. Tabl. Regne Anim., Mamm., p. 112, 1842. 
Sciitrus griseocaudatus Gkay , Voyage of 'Sulphur,' Mammalia, 11, p. 34, pi. 

13, fig. 2, pi. 18, figs. 7-12, 1843. 
Scittrus pyladii BAIV.-D, Mamm. N. Am., p. 282, 1857. 

Proc. Wash. Acad. Sci., May, 1899. 



8o NELSON 

Macroxus collicei Gray, Ann. & Mag. Nat. Hist., 3d sen, xx, pp. 421-422, 
1867 (part : var. i). 

Sciurus hypopyrrhus Allen, Mon. N. Am. Rodentia, pp. 746-750, 1877 
(part: No. 7019 from La Union, Salvador); Bull. U. S. Geol. Survey 
Terr., iv, pp. 881-882, 1878 (part); Alston, Proc. Zool. Soc. London, 
1878,' pp. 662-664 (part) ; Biol. Cent.-Am., Mamm., pp. 128-131, 1880 
(part). 

Type locality. — Salvador, Central America. Type in British Mu 
seum. 

Distribution. — Tropical forests of Salvador, vs^est coast of Central 
America. 

Characters.— Y.Vi\\x^ upperparts and base of tail dingy yellowish 
gray ; underparts and feet dull buffy ochraceous. Tail rather slender ; 
pelage thin ; hairs of back coarse, stiff and shining ; under fur short 
and thin. 

Color. — Entire upperparts, including top of head, outside of legs 
near body, and base of tail all round, nearly uniform dull grizzled 
buffy gray ; backs of ears pale rusty with basal patches of dull buff, and 
narrow indistinct borders of black ; feet, and outside of legs on lower 
half, dark ochraceous buff; paler or grayer buffy on chin, sides of nose 
and cheeks; underparts dark dingy buff; tail above, black washed with 
white ; below, with broad median area like back, bordered by line of 
black and edged with grayish white. Hairs on back black, with broad 
median rings of pale yellowish gray; under fur dark sooty plumbeous. 

Afeasurements. — Dry skin from La Union, Salvador, No. 7020 
adult, U. S. Nat. Museum : total length 545 ; tail vertebrae 2S0 ; hind 
foot 66. 

Cranial characters. — Premolars \. Skull similar to that of S. 
thomasi, but proportionately narrower and slenderer with much lighter 
jugals and smaller audital bullae. It measures: basal length 49; pal- 
atal length 26 ; interorbital breadth 20 : zygomatic breadth 34 ; length 
of upper molar series 1 1 . 

General 7zotes. — The specimen described above was compared with 
Ogilby's type in the British Museum by Mr. Thomas, who pronounces 
the two identical, and adds that the type of S. griseocaudatus Gray 
differs from them only in having the color of the belly a little richer. 
Ogilby described this species from a specimen taken during the voyage 
of the ' Sulphur,' and later Gray described S. griseocaudatus from 
another specimen collected during the same voyage. By an error, 
Ogilby stated that his specimen came from the west coast of South 
America, but Gray gave the locality of his type more correctly as the 
west coast of Central America. Lesson's S. pyladei from San Carlos, 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 8l 

Salvador, as shown by the original description, was typical 5. varie- 
gatoides ; this, with the specimen in the U. S. National Museum, 
definitely determines the region where the species is found. 
Specimen examined. — One : from La Union, Salvador. 

SCIURUS MANAGUENSIS Nelson. Rio Managua Squirrel. 

Sciurus boothicE managuensis Nelson, Proc. Biol. Soc. Washington, xii, p. 
150, June 3, 1898. 

Type locality. — Managua River, Guatemala. Type no. 62476 U. S. 
National Museum. 

Distribution.— Yinmxdi tropical forests along Managua River, north- 
ern Guatemala. 

Characters. — Size of 5". boothioe but yellower on dorsal surface 
and uniformly light buffy yellow below. Pelage rather dense; hairs 
of back coarse, stiff and shining ; tail long and narrow. Teats p. \ 



a. 4 1. 



Colors. — Upperparts, including top of nose and base of tail coarsely 
grizzled dull yellowish or grayish brown ; crown and middle of back 
washed with shining black; sides of body and outside of legs more 
suffused with yellowish ; feet of type bright buffy yellow only slightly 
grizzled (much more grizzled in two other specimens) ; ears edged 
with black and tipped with thin tuft of rusty hairs ; basal patches con- 
spicuous dull buffy yellow ; sides of head and chin dingy yellowish or 
grayish brown ; underparts, varying from rich, almost reddish buffy 
to dingy yellow; tail above black, thinly washed with white; below, 
with broad median area varying from grizzled grayish brown shaded 
with yellowish, to yellowish brown, bordered with black and edged 
with white. Hairs on back black, with broad median rings of dull 
yellowish buffy, or sometimes grayish. 

Variation.— ^-NO of the three specimens examined, including the 
type, are distinctly suffused with yellowish on back and bright yellow 
below ; the third specimen is pale brownish gray above and much 
paler, dingier yellow below, but has the lower surface of tail slightly 
shaded with rusty and the feet and back with only a slight suffusion of 

yellowish. 

Measurements.— Kx^x^i^^oi 3 adults from type locality (from dried 
skins) : total length 537, tail vertebra 270; hind foot 62.7. 

Cranial characters.— Vx^x^o\:xx?, \. Skull very similar to that of 
S. aureo<rasterhxxt somewhat narrower; inner anterior border of audi- 
tal bull/more indented, as in S. boothicc. Two adult skulls from 
the type locality average : basal length 50.2; palatal length 27; in- 



82 NELSON 

terorbital breadth 19; zygomatic breadth 33.9; length of upper molar 

series 1 1.5. 

General notes. — This squirrel was originally described as a sub- 
species of S. boothi<^ and is closely related to that species, but further 
study of the material at hand shows such strong differences that it 
seems best to regard the animals as distinct. The difference in size, 
more vivid yellow shade, and heavier wash of black on dorsal surface 
are sufficient to distinguish ^S. inanaguensis from .5. variegatoides^ 
which resembles it but is a larger, duller colored species. 

Specimens examined. — Three : all from the type locality. 

SCIURUS GOLDMANI Nelson. Goldman's Squirrel. 

Sciurtis goldmani ^YX&O-n^Yxoc. Biol. Soc. Washington, xii, pp. 149-150, 
June 3, 1898. 

Type locality. — Huehuetan, Chiapas, Mexico. Type no. 77903 
U. S. National Museum, Biological Survey Collection. 

Distribution. — Arid tropical forests along southeastern coast of 
Chiapas, Mexico, and adjacent part of Guatemala (below 1500 ft.). 

Characters. — Entire upperparts coarsely grizzled iron gray with 
an underlying yellowi'sh or buffy shade ; ear patches white and unusu- 
ally conspicuous (in winter) ; ear tufts thin, rusty ferruginous; under- 
parts, white. Pelage on dorsal surface thin ; hairs coarse, stiff and 
shining; tail long and narrow. Teats: p. i a. \ i. \. 

Color. — Winter pelage : Nose and crown dark iron gray usually 
suffused with yellowish or buffy and washed with shiny black; rest of 
upperparts rather paler, more yellowish iron gray (paler on nape and 
sides), darker and more washed with shining black along middle of 
back and rump ; fore feet paler, shading through darker gray on out- 
side of legs to yellowish gray of shoulders ; outside of thighs like flanks ; 
hind feet grizzled iron gray, toes grayish white ; ears, anteriorly dingy 
grayish with a distinct black border all around, posteriorly the upper 
half covered by a thin rusty ferruginous tuft and lower half by the 
large white basal patch ; ring around eye narrow, dull buffy brown ; 
sides of nose and cheeks dingy gray or grayish brown ; entire under- 
parts white ; tail above black, thinly washed with white ; below, me- 
dian area dull grizzled iron gray, varying to grizzled yellowish or 
rusty, with a narrow black border, broad subterminal area of black, 
and narrower edge of white. Hairs on back black with broad median 
rings of pale yellowish gray (sometimes buffy). 

Variation. — The main variation is in the color of the back which 
may be gray with a pale yellowish suffusion, or a deep, slightly rusty, 
buff grizzled with black. 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 83 

Measurements. — Average of five adults from type locality : total 
length, 550.8; tail vertebrse 280.8; hind foot 66.2. 

Cranial characters. — Premolars \. Skull closely resembling that 
of typical S. atireogaster but differing in slightly heavier rostrum, 
larger and longer audital bullse, and in having the peg-like first premolar 
set well inside the anterior angle of the second premolar. Five adult 
skulls from the type locality average : basal length 51.2 ; palatal length 
26.9; interorbital breadth 19.8; zygomatic breadth 33.9; length of 
upper molar series 11. 3. 

General notes. — Sciurus goldmani h^diX^ a superficial resemblance 
to 6". collicei nuchalis but may be readily distinguished by the black 
bordered ears, with large white basal patches, and the uniform color 
of thighs and back. The hairs on the back are coarser and stiffer. 

Specimens examined. — Ten : from Huehuetan, Chiapas ; and 
Guatemala. 

HESPEROSCIURUS subgen. nov. (p1. I, fig. 5 ; p1. II, fig. 4). 

SCIURUS GRISEUS Ord. California Gray Squirrel. 

Sciurus griseus Ord., Journ. de Phys., lxxxvii, p. 152, 1818. 

Sciurus fossor V-EAI.Y., Mamm. and Birds U. S. Expl. Expedition, p. 55, 1848. 

Sciurus heermanni LeConte, Proc. Acad. Nat. Sci., Phila., p. 149, 1852 

(type locality California). 
Sciurus fossor ant/ionyi yi^XKKS, Proc. U. S. Nat. Museum, xx, pp. 501-502, 

Jan. 19, 1898 (type from Campbell Ranch, Laguna, San Diego Co., 

California). 

Type locality. — The Dalles, Columbia River, Oregon. No type 
specimen. Named from description. 

Distribution. — Pine and oak forests of Transition (and upper 
border of Austral) zone from extreme southwestern Washington 
through western Oregon and most of California (except coast belt 
south of San Francisco) to northern Lower California, Mexico. 

Characters. — Size large ; tail long and bushy ; upperparts gray ; 
underparts white. Pelage full and soft; under fur long and thick; 
ears thinly haired. Teats : p. j- a. f i. \. 

Color. — Typical June specimens from Oregon: Upperparts, in- 
cluding top of nose and base of tail, pale gray sometimes with slight 
traces of yellowish on back ; outside of legs similar, but fore legs 
sometimes a little paler; fore feet varying from dingy grayish white 
to gray scarcely paler than back; hind feet gray, varying from a little 
paler than back to grizzled blackish gray, occasionally with white 
markings on hind feet and toes ; ears gray, sometimes suffused with 



84 NELSON 

dingy yellowish brown; basal patches small, dingy gray or yellowish 
gray ; sides of head finely grizzled gray, more whitish than back ; 
ring around eye white, poorly defined ; underparts white ; tail above 
black with a thin wash of white ; below, with broad median area dark 
grizzled gray, a rather poorly defined black border, and thin white edge. 
Hairs on back mostly black, with from one to three rings of white or 
yellowish, intermixed with others entirely black. 

Variation. — The large series examined shows but little individual 
variation. Winter specimens from northern California are somewhat 
darker, more iron gray above, with much less black on upper 
surface of tail so that the underlying gray shows through ; the ears are 
more hairy and inclining to rusty on backs and basal patches. 

Measurements. — Average of five specimens from the Columbia 
River region — near type locality of S. griseus : total length 569 ; 
tail vertebrae 270.6; hind foot 81.8. Average of five adults from San 
Diego Co., California — topotypes of '' anthonyi' : total length 566; 
tail vertebrae 284; hind foot 80. 

Cranial characters. — Premolars ^. Skull (pi. I, fig. 5 ; pi. II, 
fig. 4) rather long, tapering anteriorly; nasals long, narrowed 
posteriorly; posterior part of the braincase inflated; audital bullae 
small ; postorbital process of malar usually ending in a well developed 
point. Molars unusually massive and the peg-like second premolar 
stouter than usual. Skulls from the type locality of S. griseus 
'• anthonyi' ^w&ra^Q a little smaller than those from the Columbia 
River region, but the range of individual variation from the two 
localities is such that it is impossible to find any definite subspecific 
characters. Five adult skulls from near the type locality in the Colum- 
bia River region average : basal length 58.3 ; palatal length 32.1; inter- 
orbital breadth 20.8; zygomatic breadth 38.7; length of upper molar 
series 12.9. Five adult skulls from type locality of S. griseus 
anthonyi average: basal length 56.3; palatal length 30.2; inter- 
orbital breadth 20.9; zygomatic breadth 37.7; length of upper molar 
series 11.7. 

General tzotes. — Ord's S. griseus is based on the ' Large Gray 
Squirrel' of Lewis and Clark, which is said to have been found in a 
narrow tract of country well covered with white oak timber on the 
upper side of the mountains just below ' Columbia Falls.' From 
Lewis and Clark's narrative and the well known character of the coun- 
try it is evident that the place referred to is near The Dalles of the 
Columbia, which fixes the type locality with some certainty. 

A careful comparison of the type and topotypes of ' S. fossor an 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 8$ 

thotiyV in the National Museum, with a large series of typical S. gri- 
seus from Oregon and Washington, fails to show any character by 
which they can be satisfactorily separated. The type and some of the 
topotypes of anthojiyi can be matched by specimens taken at. the same 
season in Oregon ; I am obliged therefore to treat ant/ionyi ?i& synonym 
of S. griseus. Some specimens from the type region of '• anthonyi' 
have the feet intermediate in color hctween grise^is and nigripes} 

Spechnens examined. — Fifty-two : from many localities in Wash- 
ington, Oregon, and California. 

OTOSCIURUS subgen. nov. (p1. I, fig. 2). 

SCIURUS DURANGI (Thomas). Durango Squirrel. 

Sciiirus aberti Thomas, Proc. Zool. Soc. London, 1882, p. 372 ; Allen, 
Bull. Am. Mus. Nat. Hist., v, p. 28, April, 1893. (Not i". aberti Wood- 
house, 1852.) 

Sciurus aberti ditrangi Thomas, Ann. & Mag. Nat. Hist., 6th ser., xi, pp. 
49-50, Jan., 1893. 

Type locality. — Ciudad ranch (100 miles west of Durango City, 
Durango, Mexico. Type no. 82.3.20.16., British Museum. 

Distribution. — Pine forests of Transition and lower border of 
Boreal zones in Sierra Madre, western Durango and Chihuahua, 
Mexico (alt. 7000-11,000 feet). 

Characters. — Similar to S. aberti., but much less reddish chestnut 
on back; sides of nose to eyes usually reddish buffy, feet more or less 
grizzled gray ; tail much less full, and its lower surface uniformly 
grizzled gray ; ears smaller and narrower ; ear tufts in winter long (ab- 
sent in summer). Pelage soft and full; vmder furlong. Teats: p. \ 

a. ^ i. 1. 
21 

Color. — Summer pelage : Upperparts, including top of nose and 
base of tail, dingy gray, with dark rufous or reddish chestnut along 
back from shoulders to rump, but not reaching base of tail as in S. 
aberti \ outside of forelegs rather paler than back; fore feet white or 
pale gray; outside of hind legs like flanks; hind feet uniform 
grizzled gray like outside of thighs, or gray mottled irregularly with 
areas of white and sometimes dingy rusty ; a poorly defined black line 
along flanks separating color of upper and lower parts ; sides of nose 
(to eyes) sometimes dingy gray suffused with brownish but usually 
reddish brown ; same color shading fore part and sometimes all of 

15. fossor nigripes Bryant, Proc. Calif. Acad. Sci., 2d ser., II, pp. 25-26, 
1889. [Type from coast region south of San Francisco, probably San Mateo or 
Santa Cruz Co., Calif.] 



86 NELSON 

white ring around eve ; rest of sides of head finely grizzled gray, 
paler than back ; ears dingy gray and thinly haired, sometimes 
with traces of grizzled gray and black winter tufts ; underparts white ; 
tail at base all around like rump ; rest of tail above black, heavily 
washed with white ; below uniformly grizzled gray, with narrow indis- 
tinct black border, a well marked subterminal black area, and broad 
white edging. Hairs on back black with two to three rings of grayish 
white, the rings often becoming rufous on middle of back. 

Variation. — In some specimens the upperparts are nearly uniform 
dingy gray, the chestnut dorsal area being indicated merely by a rusty 
suffusion along the lumbar region. In those with a distinct chestnut 
dorsal area, numerous rufous ringed hairs are scattered over the back 
and flanks, giving the gray a slight brownish tinge. The color of the 
hind feet is very variable and is scarcely alike in any two specimens, 
but is never pure white as in aberti. One of the most striking and 
constant characters of this species is the entire absence of white on 
the underside of the tail. 

JMeastirements. — Average of five adults from vicinity of type lo- 
cality : total length 4S6.4; tail vertebrse 235.4; hind foot 71.2. Five 
adult topotypes of 6". ai^er// average : total length 510 ; tail vertebra; 
229.8; hind foot 75.6. 

Cranial characters. — Premolars y* Skull (pi. I, fig. 2) generally 
similar to that of S. aberti but somewhat smaller, with notably 
smaller molars, and shorter and more slender first premolar ; audital 
bullae relatively larger; braincase a little less draw^n out posteriorly. 
Five adult skulls from vicinity of type locality average as follows: 
basal length 50.1 ; palatal length 27.3; interorbital breadth 19.8 zy- 
gomatic breadth 34.5; length of upper molar series 10.8. Five adult 
skulls of 6^. aberti from type locality average: basal length 52; pa- 
latal length 27.8; interorbital breadth 19.8; zygomatic breadth 35.1 ; 
length of upper molar series 11.2. 

General notes. — The characters which separate this squirrel fi'om 
S. aberti are so constant in the series before me that it seems best to 
consider it a distinct species. Each species has a well defined range, 
there being a broad gap in northern Chihuahua and southern Arizona 
in which neither occurs. 

Specimens exaiuined. — Thirty-two: from El Salto (near Ciudad 
ranch), Durango; Sierra Madre and near Guadalupe y Calvo, Chi- 
huahua (in southwestern corner of State). 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 87 

Subgenus TAMIASCIURUS Trouessart (p1. I, fig. 8). 
SCIURUS DOUGLASI MEARNSI (Townsend). Mearns' Squirrel. 

Sciurus hiidso-niiis mearnsi Townsend, Proc. Biol. Soc. Washington, xi, p. 

146, June 9, 1897. 
Sciurus mearnsi h.iA.^-ii, Bull. Am. Mas. Nat. Hist., N. Y., x, pp. 286-287. 
1898. 
Type ^oca//f_y. — San Pedro Martir Mountains, Lower California 
(about 7000 ft. alt.). Type no. \UH- U. S. National Museum. 

Distribution.— V\xi& forest of San Pedro Martir Mountains, Lower 
California, Mexico. Transition zone. 

Characters. — Generally similar to 5'. dotiglasi albolirnbatus but 
grayer, with feet pale yellowish, or buffy white. Pelage soft and 
dense ; under fur long ; tail short and bushy. 

Color. — Entire upperparts, including top of nose, outside of fore- 
legs and thighs pale dingy gray, with pale yellowish or rusty suffusion 
extending from nape along back and out on middle of basal half of 
tail; sides of nose pale buffy whitish; sides of head grizzled gray, 
paler than back ; ring around eye whitish ; ears, in front, like sides 
of head, behind like crown, with well marked tuft of black hairs, 
slightly grizzled with gray or dingy fulvous; line along flanks black, 
distinctly separating color of back from that of underparts ; feet pale 
yellowish white ; fore feet inclining to buffy ; underparts dingy white ; 
under fur plumbeous, showing through white surface; tail above, 
median line of basal half like middle of rump, but edged and slightly 
grizzled with white ; rest of upper surface black washed with white 
tail below, median area of basal two-thirds dingy grizzled gray bor- 
dered with black (the black also extends over most of outer third) and 
narrowly edged with white. Dorsal hairs black with broad median 
and narrow subterminal rings of pale dull grayish or dingy yellowish 
(the latter mainly along middle of back) . 

Variation.— i:\\c three specimens of this squirrel before me were 
taken in April and May and show little variation. They are paler 
than typical specimens of albolimbatus taken at the same season but 
are not strikingly different. 

Measurements.— KvQxaz'^ of three adults from type locality (from 
dry skins): total length 305 ; tail vertebrae HI.3; hind foot 50.6. 
(The total length and tail measurements are, no doubt, too short.) 

Cranial characters.— ?x^vno\ax?, \. Skull (pi. I, fig. 8) much like 
that of S. d. albolijnbatus. The type measures : basal length 41 ; pa- 
latal length 35; interorbital breadth 14.5; zygomatic breadth 28; 
length of upper molar series 8. 

specimens examined.— ThveQ : all from type localit}-. 



88 NELSON 

AR^OSCIURUS subgen. nov. (p1. I, fig. 3.) 
SCIURUS OCULATUS Peters. Black-backed Squirrel. 

Sciurus r«//5/r«/z^J LiCHTENSTEiN, Abhandl. K. Akad. Wiss., Berlin (1827), 

p. 116, 1830. (Not S. capistratus Bosc, 1802.) 
Sciurus carolinensisSxvssv^-E., Rev. et Mag. de Zool., 2e ser., xiii, p. 4, 1861. 

(Not S. carolincnsis Gmelin, 1788.) 
Sciurus oculatus Peters, Monatsber. K. Akad. Wiss., Berlin 1863, p. 63. 
Sciurus hypopyrrhus Allen, Bull. U. S. Geol. Survey Terr., iv, pp. 881- 

882, 1878 (part). 
Sciurus niger melanonotus Thomas, Proc. Zool. Soc. London, pp. 73-74, pi. 

VI, 1890; Allen, Bull. Am. Mus. Nat. Hist., v, p. 30, 1893 ; Ibid., ix, 

p. 198, 1897. 

Type locality. — Mexico, probably near Las Vigas, Vera Cruz. Type 
no. 1434 Berlin Museum. 

Distribution. — Pine and oak forests of Transition and Boreal zones 
in northern Puebla, western Vera Cruz (Cofre de Perote — Mt. Ori- 
zaba), Hidalgo, eastern Queretaro, and southeastern San Luis Potosi, 
Mexico (alt. 6000-13,000 feet). 

Characters. — Size large ; upperparts gray with large black or 
blackish area along middle of back ; belly buffy. Pelage rather soft 
and dense; under fur long; tail long and full. Teats: p. ^ a. f i. \. 

Color. — Crown between ears, and broad band along middle of back 
from shoulders to base of tail, black or blackish, shading on edges to 
dark gray like remainder of upperparts ; ring around eye well marked, 
buffy whitish or buffy ; cheeks usually grizzled gray like sides of neck 
but sometimes washed with buff ; ears dingy gray frequently washed 
with dull buff of variable intensity; basal ear patch varying from 
dingy white to dark buffy (sometimes absent in summer) ; feet varying 
from grizzled gray washed with buffy to rich buff shading to gray on 
outside of fore legs ; outside of lower hind legs varying from gray like 
rest of thigh to dark rusty brownish. Underparts varying from white 
with pale dull buffy suffusion to rich ochraceous buff ; tail above black, 
heavily washed with white ; below, with broad median area of grizzled 
yellowish gray, bordered with black and heavily edged with white. 
Hairs of back black, with one or two rings of gray, yellowish gray or 
brownish gray, mixed with other hairs wholly black. 

Variation. — The black dorsal band is usually present, sometimes 
continuous from crown to tail (as in a specimen from Tulancingo), 
and varies from 25 to 50 mm. in width ; but in two specimens from 
the Cofre de Perote, Vera Cruz, and in nearly all from Pinal de 
Amoles, Qiieretaro, it is i^epresented only by a black wash. The buff 
on underparts of the latter specimens is decidedly richer than on ordi- 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 89 

nary examples with black backs, and is equally intense in specimens 
from Encarnacion, Hidalgo, which have the well-marked black dorsal 
band. Two specimens from Villar, San Luis Potosi, in worn summer 
pelage, differ in being uniform gray on back, scarcely darker along 
median line, but they agree with the Pinal de Amoles specimens in 
the rich, buffy underparts. The buff on feet accompanies and varies 
in intensity with same color on underparts. The only melanistic 
specimen in the series is from Pinal de Amoles, Qiieretaro. 

JMeastn'etncizts. — Average of five adults from type locality : total 
length 542.8; tail vertebras 269; hind foot 72.7. 

Cranial characters. — Premolars \. Skull (pi. I, fig. 3) propor- 
tionately broader and heavier than that oihidoviciamis ; rostrum shorter 
and heavier ; interorbital breadth greater ; top of braincase broader and 
less convex on interparietal outline ; occiput decidedly broader and 
more depressed ; audital bullae appi^eciably larger and more drawn out 
anteriorly and posteriorly. Three adult skulls from the type locality 
average as follows: basilar length 54.6; palatal length 28.5; interor- 
bital breadth 20.3 ; zygomatic breadth 36.3 ; length of upper molar 
series 11. 

General notes. — Peters described Sciurus octilatus in 1864 from a 
specimen collected by Deppe in eastern Mexico. Thomas redescribed 
the species in 1S90 as 6". niger fnelanonotus., from specimens taken at 
Las Vigas, Vera Cruz. Specimens from Las Vigas agree perfectly 
with the original description of S. oculatits^ and since this locality is on 
the route followed by Deppe it may be considered the type locality. 

Habits. — This species properly belongs to the pine forests of the 
Transition and Boreal zones from 7500-12,000 feet, but at Villar, San 
Luis Potosi, near the northern border of its range, we found it in the 
oaks of the Upper and Lower Austral zones (5500-6000 feet) where 
it was feeding on acorns and wild figs in the canyon bottoms. Ordi- 
narily its main food supply is obtained from various species of pines. 

Specimens examined. — Forty-six : from Mt. Orizaba, Puebla ; Cofre 
de Perote and Las Vigas, Vera Cruz ; Real del Monte, Tulancingo 
and Encarnacion, Hidalgo; Pinal de Amoles, Qvieretaro ; Villar, San 
Luis Potosi (6000 feet). 

SCIURUS OCULATUS TOLUC^ Nelson. Toluca Squirrel. 

Schtrus octilatus tolucce Nelson, Proc. Biol. Soc. Washington, xii, pp. 148- 
149, June 3, 1898. 
Type locality. — North slope of the Volcano of Toluca, State of 
Mexico, Mexico. Type no. 55927 U. S. National Museum, Bio- 
logical Survey collection. 



90 



NELSON 



Distribution. — Pine and oak forests of Transition and Boreal zones 
on tableland slope of the Sierra Madre in the vState of Mexico, from 
the Volcano of Toluca north to border of Michoacan ; also arid moun- 
tains of southern and western Queretaro, central and eastern Guana- 
juato, and southern San Luis Potosi, Mexico (alt. 7500— 12,060 feet) . 

Characters. — Paler than S. oculattis, with a wash of blackish, or 
blackish brown along middle of back ; underparts dingy whitish, with 
only a faint suffusion of buffy. Pelage and teats as in S. oculatus. 

Color, — Top of head and broad median line down back to base of 
tail, gray with a faint blackish or dull brownish wash shading laterally 
into clearer grizzled gray ; latter color, however, with slight shading of 
yellowish on subterminal rings of some hairs ; ring around eye grayish 
white with pale buffy shade ; rest of sides of head dingy gray suffused 
with dull buffy or pale brownish ; ears dull gray shaded with buffy ; 
patch behind ear dingy whitish ; feet grayish white with buffy wash, 
usually deeper than on underparts ; outside of fore legs and thighs like 
flanks ; thighs near feet suffused with yellowish brown ; tail above 
black, heavily washed with white ; below, along median line grizzled 
yellowish gray or pale yellowish brown, bordered with black and 
broadly edged with white. Hairs of back black with one or two i-ings 
of gray, yellowish or brownish gray, mixed with other hairs wholly 
black. 

Variation. — A single melanistic specimen from the type locality is 
the only one seen. The four normal specimens show little variation, 
and this mainly in the amount of buffy on the feet and in the intensity 
of the dark wash along middle of back. 

Measurements. — Average of four adults from type locality : total 
length 531 ; tail vertebrae 263 ; hind foot 68. 7. 

Cranial characters. — Premolars \. Skull much like that of S. 
oczdatus., but in nearly all of the specimens examined the nasals are 
much narrower posteriorly with a corresponding increase in breadth of 
the premaxillaries. Two adult skulls from type locality average as 
follows : basilar length 54 ; palatal length 29 ; interorbital breadth 30.5 ; 
zygomatic breadth 36.7; length of upper molar series 11. 

Ge7teral notes. — This form resembles specimens of S. oculatus 
from Pinal de Amoles very closely in the color of the back, but may 
be distinguished at once by the whitish ear patches and whitish ven- 
tral surface. It was named for the Volcano of Toluca, the type 
locality. » 

Specimens exa?ni?ied. — Seven: from Volcano of Toluca, Mexico; 
Tequisquiapan, Qiieretaro ; mountains north of Guanajuato city, 
Guanajuato, Mexico. 



SQtJIRRELS OF MEXICO AND CENTRAL AMERICA QI 

SCIURUS ALLENI Nelson. Allen's Sqinrrel. 

'Sciurus carolinensisll' Baird, Mamm. N. Am., pp. 263-264, 1857 (Santa 

Catarina, Nuevo Leon, Mexico). 
Sciurus carolinensis var. carolinensis Allen, Mon. N. Am. Rodentia, pp. 

706-709, 716, 1877 (part: from. Nuevo Leon, Mexico). 
Sciurus carolinensis Alston, Proc. Zool. Soc. London, pp. 658-659, 1878 ; 

BioL Cent. -Am., Mamm., pp. 124-125, June, 1880 (part: from Nuevo 

Leon, Mexico). 
Sciurus arizonensis Allen, Bull. Am. Mus. Nat. Hist., N. Y., iii, p. 222, 

May, 1 89 1 (part : from San Pedro Mines, Nuevo Leon, Mexico). 
Sciurus alleni Nelson, Proc. Biol. Soc. Washington, xii, pp. 147-148, June 

3, 1898. 

Type locality. — Monterey, Nuevo Leon, Mexico. Type no. | ^ ^ | j 
U. S. National Museum, Biological Survey Collection. 

Distribution. — Open pecan and other forests of Lower Sonoran 
zone near Monterey, Nuevo Leon, extending up to oak and pine forests 
of Transition zone near Victoria and Miquihuana, Tamaulipas, 
Mexico (alt. 2000-8500 ft.). 

Characters. — Upperparts nearly uniform grayish brown or yellowish 
brown, much as in Sciurus carolinensis; feet gray ; underparts white. 
Pelage on back soft and rather dense; tail rather full. Teats: p. \ 
a.fi.i. 

Color. — Winter pelage : Entire upperparts yellowish brown, finely 
grizzled with gray and black, usually darker along back and grayer 
along sides; top of head similar, but usually a little darker; eye with 
distinct ring of dingy whitish shaded with buff on outer border ; sides 
of head grizzled dusky gray, often suffused with yellowish brown ; 
ears and basal patch brownish gray ; fore feet and outside of fore legs 
whitish gray, frequently more or less washed with buffy ; hind feet 
whitish gray, usually with a spot of dark buffy on middle of upper 
surface ; outside of thighs like flanks but often with a browner shade 
near feet ; underparts white ; color of upper- and lowerparts 
usually separated by a narrow line of pale grayish ; base of tail all 
around like back ; tail above black, heavily washed with white, the 
yellowish brown or yellowish gray under color often showing through ; 
below with broad median area of grizzled yellowish brown or yellow- 
ish gray, narrowly bordered with black and edged with white. Hairs 
of back black, with one and often two rings of gray, buffy, or buffy 
brown, the two colors sometimes on same hair and sometimes on 
distinct hairs. The pelage in summer Is darker and more yellowish 
brown than in winter — due to absence of most of the gray or white 
tips to hairs. 



92 NELSON 

Variation. — The striking differences in proportions between speci- 
mens from the lowlands near Monterey and those from the mountains 
near Miquihuana (alt. 8500 ft.) as shown by the average measure- 
ments are not accompanied by similar differences in color. The upper- 
parts are sometimes grizzled brown and vary from that to nearly clear 
gray. A specimen from the San Pedro Mines, Nuevo Leon, has 
the upperparts dark yellowish brown, darkest (thinly washed with 
black) on top of head. The eye is surrounded by a ring of dark 
buff, the fore feet are washed with buff and the hind feet with grayish 
white. Another specimen in similar pelage was taken at Miquihuana, 
Tamaulipas, in June ; a winter specimen from Rio San Juan, Nuevo 
Leon, is almost as dark but has grayer sides and feet. No signs of 
melanism seen. 

Measuretnents. — Average of five adults from vicinity of type local- 
ity : total length 471 ; tail vertebrae 217; hind foot 60.6. Average of 
five adults from mountains near Miquihuana, Tamaulipas : total length 
465; tail vertebrae 230.4; hind foot (i>,.^. 

Cranial characters. — Premolars \. Skulls of 6'. alleni are only 
distinguishable from those of S. oculatus by their smaller size. Five 
adult skulls from region of type locality average : basilar length 
50.4; palatal length 26.3; interorbital breadth 18.4; zygomatic 
breadth 33.7; length of upper molar series 10.5. Five adult skulls 
from near Miquihuana average: basal length 50; palatal length 25.6; 
interorbital breadth 18. i; zygomatic breadth 33.7; length of upper 
molar series 10.3. 

General notes. — Sciurus alleni bears a close superficial resem- 
blance to 6". caroline7isis of Texas, but has only a single premolar. 
From S. o. tolucce it differs mainly in smaller size, grayer feet and whiter 
belly. The type of this species came from near Monterey, Nuevo 
Leon. By a slip of the pen in the original description the type locality 
was given as Monterey, Tamaulipas. Baird called attention to this 
squirrel in 1857, under the name ' Sciurus carolinensisPP' and gave 
the essential characters which separate it from S. caroline?isis. Sub- 
sequent authors have referred it to the same species or to S. arizon- 
ensis., but a series in the collection of the Biological Survey shows that it 
is a well defined species most nearly related to S. octilatus. Neither 
S. carolinefzsis^ nor any close relative of that species occurs in 
Mexico. 

Specimetis examitied. — Twenty-two : from Monterey, Linares, Rio 
de San Juan, and San Pedro Mines, Nuevo Leon ; near Victoria and 
Miquihuana, Tamaulipas. 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 93 

SCIURUS NAYARITENSIS Allen. Nayarit Squirrel. 

Scinrus alskmi Allen, Bull. Am. Mus. Nat. Hist., N. Y., 11, pp. 167-170, 

October, 1889 (Not S. alsioJii And&rson, 1878). 
Sciurus nayaritensis Allen, Bull. Am. Mus. Nat. Hist., N. Y., 11, p. vii, 

footnote, Feb. 1890 (new name for S. ahtoni Allen); Ibid., iii, p. 

185, 1890; Ibid., V, p. 30, April, 1893. 

Type locality. — Sierra Valparaiso, Zacatecas, Mexico. Type no. 
1985 American Museum of Natural History, New York. 

Distributio7i. — Pine and oak forests of the Transition Zone in the 
Sierra Madre and outlying spurs of western Zacatecas, southern Du- 
rango, eastern Tepic and southern Jalisco, Mexico (alt. 6500-9000 ft.) . 

Characters. — Size large ; back dark gray ; ears rusty, belly and feet 
white. Tail bushy; ears thinly haired; pelage thick and soft; under 
fur long. Teats : p. i a. |^ i. \. 

Color. — Upperparts dark gray, with underlying rusty yellowish 
showing through ; broad ring around eye white ; rest of sides of head 
gray, frequently shaded with rusty brown ; ears varying from dingy 
grayish to dull rusty brown ; outside of fore legs varying from white to 
grayish white, or white suffused with buffy ; fore feet dingy white often 
suffused with buffy ; outside of hind legs paler or more washed with 
whitish than back ; hind feet grayish white, often washed with buffy ; 
toes whitish suffused more or less with buffy ; underparts white ; tail 
above at base like back, rest of upper surface black heavily washed with 
white ; below, with broad ferruginous median area, heavy black border, 
and broad white edge, the white often extending as a wash over the 
entire lower surface. Hairs on back rusty yellow (sometimes ferru- 
ginous) with broad subterminal black rings and narrow white tips. 

Variation. — Among 17 winter specimens from the type locality 10 
have a more or less strong wash of rusty on the back part of crown and 
nape — thus forming a poorly defined nape patch ; and one has a simi- 
lar rusty wash along middle of lumbar region. This winter series is 
more whitish on the back than summer specimens from the Nayarit 
Mts. at Santa Teresa, Tepic ; and a series taken in September near Pla- 
teado, Zacatecas, agrees with the one from Santa Teresa. These 
summer skins have numerous scattered hairs on the back entirely 
black ; others rusty yellow, or dull rufous, with sub-basal and subter- 
minal black rings, with or without white tips ; the white tips when 
present generally smaller than in the Valparaiso specimens. The re- 
sult is a generally darker, more rusty, back and an increase of buffy or 
rusty buff on feet and outside of fore legs. The surface of the tail has 
less white and the ferruginous median area below is consequently more 



94 



NELSON 



distinct. This is probably the summer pelage but may possibly rep- 
resent a local form. Two specimens from Santa Teresa have the 
entire underparts dark rusty buffy and are the only ones showing this 
color below. 

Measurements. — Average of five adults from type locality : total 
length 565.8; tail vertebrae 272; hind foot 77.5. 

Cranial characters. — Premolar \. Upper molars broader and 
heavier than in S. oculatiis., but otherwise the skulls are scarcely dis- 
tinguishable. Five adult skulls from the type locality average : basi- 
lar length 55.5 ; palatal length 28.4; interorbital breadth 20.7 ; zygo- 
matic breadth 37.1 ; length of upper molar series 11.7. 

General notes. — The type of 6". alstoni Allen came from the Sierra 
Valparaiso, but in renaming the species Dr. Allen called it S. 
nayaritensis from the Nayarit Mts., a part of the Sierra Madre about 
100 miles southwest of the type locality. 

Specimens examiitcd. — Forty-one : from Sierra Valparaiso, Sierra 
Madre, and Flateado, Zacatecas ; Sierra Madre, northern Tepic ; 
Sierra de Juanacatlan and Barranca Beltran (east base Sierra Nevada 
de Colima), Jalisco. 

SCIURUS APACHE Allen. Apache Squirrel. 

Sciurus griseoflavus Thomas, Proc. Zool. Soc. London, 1882, p. 372 (not 

6". griseoflavus Gray, 1867). 
Sciurus niger ludovicianus Thomas, Proc. Zool. Soc. London, 1890, p. 73, 

footnote. 
Sciurus apache Allen, Bull. Am. Mus. Nat. Hist., N. Y., v, p. 29, March 

16, 1893. 

Type locality. — Mountains of northwestern Chihuahua (near Ba- 
vispe River .?) , Mexico. Type no. ff^f , American Museum of Natural 
History, New York. 

Distribution. — Mixed oak and pine forests of Transition zone in 
the Sierra Madre of western Durango and Chihuahua, eastern Sonora 
and northeastern Sinaloa, Mexico, and the Chiricahua Mountains of 
southern Arizona. 

Characters. — Size large, about equalling S. ludovicianus to which 
it bears a strong general resemblance in color, but is readily distinguish- 
able by its gray ears, darker, more iron gray upperparts, dull rusty 
ferruginous hind legs and black upper surface of the tail which is 
thinly washed with pale yellowish white, or rusty buff. Pelage thick 
and soft; ears thinly haired. Teats : p. i a. f i. \. 

Color. — Sumjner pelage : Upperparts including top of nose and 
base of tail dark, sometimes almost iron gray, often washed but never 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 95 

strongly shaded with yellow. Crown and back darker, often becoming 
blackish along middle of rump and on base of tail ; top of back some- 
times, and flanks commonly, washed with pale yellowish ; sides of head 
grizzled gray and dark fulvous, the gray sometimes predominating; 
ring around eye well marked and varying from buffy white to rich 
fulvous buffy ; ears dingy gray sometimes suffused with pale buffy ; 
a scanty basal patch of dull buffy or orange buff sometimes present ; 
feet and often most of fore legs and entire underparts varying from 
dark dull buffy yellow to rich orange yellow, sometimes suffused with 
rusty; hind feet usually a little darker than fore feet; outside of hind 
legs varying from gray suffused with dull rusty to uniform rusty some- 
times with a strong tawny rufous shade that extends over inside of 
thighs ; tail above black, with a wash varying from pale yellowish white 
to rusty yellow; below with broad median area varying from yel- 
lowish rusty to dull rusty rufous with a broad indistinct black border 
and broad edge of pale yellowish, or rusty buffy, the latter colors often 
forming a wash over entire lower surface. Hairs of back black, with 
small white or pale yellowish tips and broad buffy or yellowish basal 
or sub-basal rings. 

Variation. — The amount of individual variation is comparatively 
small ; the back becomes a little paler or darker, the color on outside 
of thighs more or less intense, and color of lower parts varies in in- 
tensity as already described. 

Measurements. — Average of five adults from northern Chihuahua : 
total length 565.8; tail vertebrae 279; hind foot 79.2. 

Cranial characters. — Premolars \. Skull much larger than that of 
S. oculatus., with audital bull« proportionately smaller. Five adult 
skulls from western Durango average as follows : basilar length 56.4 ; 
palatal length 28. 7; interorbital breadth 21.5; zygomatic breadth 
37.5 ; length of upper molar series 11. 9. 

General notes. — Although the color of Sciurus apache is very 
much like that of 6'. ludovicianus., the form of the skull shows that it 
belongs to the subgenus Arceosciurus., of which S. oculatus is the 
type. 

During the summer of 1898 we found S. apache common in the 
mixed forest of pines and oaks on the mountains of western Durango. 
They live in hollow oaks, entering by a knot hole or broken branch 
and were rarely seen on the pines. The upper limit of their range 
overlaps the lower limit of 5. durangi but neither occupies much 
territory of the other. The type of this fine squirrel came from the 
region once occupied by the Apache Indians for whom it was named. 

Proc. Wash. Acad. Sci., May, 1899. 



^6 NELSON 

Spect/tiefis exatnined. — Thirty-three : from El Salto (southwest of 
Durango City), Durango ; near Guadalupe y Calvo, Bavispe River, 
and Sierra Madre near Arizona border, Chihuahua ; Sierra de Choix, 
northeastern Sinaloa, Mexico ; and the Chiricahua Mountains, Arizona. 



SCIURUS ARIZONENSIS HUACHUCA Allen. 
Huachuca Squirrel. 

Sciurus arisonensis huachuca ^\.i.Kii, Bull. Am. Mus. Nat. Hist., N. Y., vi, 
p. 349, Dec. 7, 1894; Ibid., vii, p. 245, 1895. 

Type locality. — Huachuca Mountains, southern Arizona. Type 
no. ^^^ American Museum of Natural History, New York. 

Distribution. — Pine and oak forests of Transition zone, in north- 
eastern Sonora, Mexico, and Huachuca Mountains, southern Arizona. 

Characters. — Generally similar to S. arizonensis but with a broad 
band of gray over back of neck and shoulders, separating the median 
grizzled yellowish or pale rusty area into a narrow patch on crown 
and ears and a larger one on lumbar region and rump. Pelage full 
and soft; tail long and bushy. Teats: p- y a. f i. \. 

Color. — May specimens from Ft. Huachuca, Arizona : upperparts, 
including top of nose and base of tail, pale grizzled gray with rusty 
yellow wash on back of crown, lumbar region and rump ; sides of 
neck, flanks, and outside of hind legs somewhat paler than top of 
shoulders; fore feet and outside of legs grizzled grayish white, some- 
times pale gray ; hind feet pale grizzled gray ; ring around eye whitish, 
or slightly buffy ; sides of head whitish gray often with postocular 
yellowish brown suffusion ; ears dingy grayish or dull yellowish, some- 
times with small patch of dull gray or rusty yellow behind base ; under- 
parts white ; tail above black washed with white, heaviest along 
border; below, broad median area grizzled rusty, dull orange yellow 
or yellowish brown, with heavy black border and broad white edge. 
Hairs on back black with white tips and broad yellow sub-basal or 
basal rings, or with subterminal buffy yellow rings, mixed with other 
hairs wholly black. Winter pelage similar to that of summer but a 
little grayer on sides of body and outside of legs and feet ; ears more 
thickly haired and dull rusty with basal patches of same color ; white 
on tail more distinct. 

Variation. — The type of huachuca has a dull yellowish wash on 
crown, and the ears and basal ear patches are rusty ; the rest of the 
upperparts are grizzled gray, darker along middle of back where an 
intermixture of rusty forms a small irregular patch ; the flanks, outside 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 97 

of legs and feet are paler. This specimen is exceptionally gray on 
the back, as it lacks the usual well defined yellowish area on rump. 
Several worn summer specimens from Huachuca have the area about 
the mouth and inside of fore feet and legs stained deep brown from 
the juice of walnut shells, and the underparts of a number of speci- 
mens are dingy buffy, probably due to the same cause. 

Measurements. — Average of four adults from type locality : total 
length 517; tail vertebrae 247; hind foot 70.5. 

Cranial characters. — Premolars \. Skull similar to that of S. ocu- 
latus., but rostrum heavier ; parietal region slightly more inflated ; oc- 
ciput higher and narrower ; foramen magnum higher, narrower and 
obtusely triangular; audital bulke decidedly smaller. Four adult 
skulls from type locality average : basal length 53.5 ; palatal length 
27.5; interorbital breadth 19.9; zygomatic breadth 36.5; length of 
upper molar series 10.9. Four adult skulls of arizonensis from near 
type locality average : basal length 53.2; palatal length 27.1; inter- 
orbital breadth 20.1 ; zygomatic breadth 36.4; length of upper molar 
series 11. 4. 

General notes. — This is not a strongly marked subspecies but the 
separation of the yellowish dorsal area by the gray band across the 
shoulders and neck seems to be constant and is accompanied by dif- 
ferences in size. A specimen from the Santa Catalina Mountains, 
Arizona, between the type localities of arizonensis and huachuca., is 
exactly intermediate between the two forms. 

Specimens examined. — Twenty-six : from Huachuca Mountains, 
Arizona, and Sonora, Mexico (32 miles south of Nogales). 

Subgenus PARASCIURUS Trouessart. (p1. I, fig. i.) 

SCIURUS LUDOVICIANUS LIMITIS Baird. 
Texas Fox Squirrel. 

Scturus limiiis Baird, Proc. Acad. Nat. Sci, Phila., vii, p. 331, 1855 ; 

Mamm. N. Am., p. 256, 1857. 
Scturus iiiger vzx. ludoviciaiius Allen, Mon. N. Am. Rodentia, pp. 724-731, 

1877 (part : southwest Texas and Nuevo Leon, Mexico). 

Type locality. — Devils River, Texas. Type no. 351 U. S. Na- 
tional Museum. 

Distribution. — Wooded parts of Lower Sonoran zone in southwest- 
ern Texas and adjacent parts of Nuevo Leon and Coahuila, Mexico. 

Characters. — Similar to S. ludovicianus but considerably smaller, 
with slenderer tail, thinner pelage and paler colors. Pelage thin, hairs 
of back rather harsh ; under fur thin. Teats : p. | a. f i. }. 



pS NELSON 

Color. — Entire dorsal surface, including top of nose and base of tail, 
vmiform pale yellowish gray ; sides of head dull, dark buffy yellow, 
grizzled on cheeks with gray and black, sometimes with a slight red- 
dish shade ; ring around eye buffy ; ears dingy rusty, or buffy yellow ; 
feet dark yellowish buffy shading into gray on upper part of fore legs ; 
outside of hind legs like back but with a buffy or dull rusty wash near 
feet ; underparts varying from orange buff to pale, slightly reddish 
rusty ; tail above, grizzled black and gray with a thin wash of grayish 
or pale grayish yellow ; below, with broad median area of rusty fer- 
ruginous or yellowish rusty, often grizzled with black, a narrow black 
border and thin edging of grayish or pale yellowish. Hairs on back 
black, with broad subterminal and basal or sub-basal rings of pale yel- 
lowish or buffy ; along sides of body often tipped with white. 

Variation. — The series at hand shows very slight individual and 
little if any seasonal variation. The difference lies mainly in the in- 
tensity of the yellow or rusty and the amount of grayness on the back, 

Measurements. — Average of five adults from region of type locality : 
total length 482.2 ; tail vertebrae 234; hind foot 65.2. 

Cranial characters. — Premolars \. Compared with S. ludovici- 
anus the skull (pi. I, fig. i), is very much smaller. Two adult skulls 
from Fort Clark, Texas, average : basal length 50 ; palatal length 25.5 ; 
interorbital breadth 18; zygomatic breadth 33.5; length of upper 
molar series 10.5. 

Specimens examitied. — Fourteen : from near the mouth of Devils 
River, Fort Clark, and Nueces River, Texas. 



Subgenus GUERLINGUETUS Gray. (p1. I, fig. 7.) 

SCIURUS ^STUANS HOFFMANNI Peters. 
Hoffmann's Squirrel. 

Sciurus cestuans var. koffmaftni Vki^^S, Monatsber. K. Akad. Wiss., Berlin, 

1863, pp. 654-655 ; Thomas, Proc. Zool. Soc. London, 1880, p. 401 

{Macroxus griseogena Gray, referred to this form). 
Macroxus xanthotus Gray, Ann. & Mag. Nat. Hist., 3d ser., xx, p. 429, 

1867. 
Macroxus griseogena Gray, Ann. & Mag. Nat. Hist., 3d sen, xx, pp. 429- 

430, 1867 (part : Costa Rica). 
Sciurus ceshians var. rufoniger h.iA.Y.'n, Mon. N. Am. Rodentia, pp. 757-763, 

1877 (part : Costa Rica). 
Sciurus griseoge7iys Alston, Proc. Zool. Soc. London, pp. 667-668, 1878 

(part : Costa Rica, Veragua and Panama.) 
Sciurus hoffmanni Allen,- Bull. U. S. Geol. Survey Terr. iv. pp. 885-886, 

1878. 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA 99 

Sciuriis astiians Alston, Biol. Cent. -Am., Mamm , pp. 132-133, 1880 (part : 

Costa Rica and Panama). 
Sciiirus astnans }toffma7itii h.\x.^-^, Bull. Am. Mus. Nat. Hist., N. Y., in, pp, 

206-207, 1891 ; Ibid., IX, p. 35, 1897 ; Alfaro, Mamiferos de Costa 

Rica, p. 31, 1897. 

Type locality. — Costa Rica, Central America. 

Distribution. — Humid tropical forests of Costa Rica, south to Val- 
ley of upper Cauca River, Colombia. 

Characters. — Size similar to that of ^S". cestuafis^ but color much 
darker and more rusty brown on back, more ferruginous red on under- 
parts, and tail heavily w^ashed with bright ferruginous. Tail broad 
and flat ; pelage soft and rather thin. 

Color. — Entire upperparts, including top of nose and base of tail, 
finely grizzled dark yellowish or rusty brown; top of head and middle 
of back usually a little darker than sides and sometimes blackish ; out- 
side of legs and feet similar to back but often more yellowish or rusty ; 
ears usually a little darker rusty than top of head, with small basal 
patch of dingy fulvous or dull rusty ; sides of head more yellowish or 
rusty than back ; ring around eye dark buffy or sometimes rusty yellow- 
ish ; chin and throat dull buffy yellowish, sometimes suffused with 
rusty; rest of underparts varying from dull rusty buff to deep ferrugi- 
nous ; tail above black, heavily washed with bright ferruginous, some- 
times becoming paler but always strongly ferruginous ; below with 
broad median area of grizzled black and dark yellowish brown, bordered 
with black and edged with ferruginous. Hairs on back, black with 
narrow sub-terminal rings of buffy or rusty yellow, sometimes with 
similar sub-basal rings. 

Variatiojz. — The amount of variation seems to be comparatively 
small. Specimens from Talamanca and Santa Clara in eastern Costa 
Rica are darker than those from elsewhere in that country. Some 
from the valley of the upper Cauca River, Colombia, are a little paler 
or more olivaceous than Costa Rica specimens, but others from the 
same district are indistinguishable. 

Measurements. — Averages of four adults from eastern Costa Rica : 
total length 426.6; tail vertebrte 187; hind foot 54.3. 

Cranial characters. — Premolars \. Skull (pi. I., fig. 7) rather 
broad, braincase arched and inflated over interparietal region and con- 
stricted posteriorly, so that the occipital region is a little drawn out ; 
audital bullae small and rounded. Five adult skulls from central and 
eastern Costa Rica average: basal length 43.2; palatal length 23.3; 
interorbital breadth 17; zygomatic breadth 31.3; length of upper 
molar series 9. 



lOO NELSON 

General notes. — A specimen of hoffmatiiti from Costa Rica (no. 
12058 U. S. Nat. Museum) has been compared with the type of Ma- 
croxus xanthohis Gray by Mr. Thomas, who writes that they are the 
same except that Gray's type is immature. The distribution of M. 
griseogena Gray was given as extending from Venezuela to Mexico, 
but it is scarcely necessary to state that no species of squirrel has this 
range. Mr. Thomas writes that the question of the type of griseogena 
is very difficult, but it seems best, as with tephrogasier., to take the 
first named specimens (Dyson's) as the type (B. M, 47.2. 1.3). This 
is the only one mentioned by Gray which exactly agrees with his de- 
scription, and since Venzuela specimens agree best with 47.2. i. 3. 
that country becomes the type locality for M. griseogena. Mr. 
Thomas compared a specimen of .S". cBstuans from Venezuela (no. 
1 1 733 U. S. Nat. Museum) with the type of griseogena and found 
them to agree very closely. The Venezuela squirrels seem to repre- 
sent a form of cestuans paler and less rufous than hoffnianni. 

Specimens examined. — Twenty-five : from Boruca, Talamanca, 
Luis, San Jose and Santa Clara, Costa Rica; Rio Lima, Las Pabas, 
Los Tambos, Rio Zapata, Rio Pescado and upper Cauca Valley near 
Call, Colombia. 

SCIURUS RICHMOND! Nelson. Richmond's Squirrel. 

Sciurus richmondi Nelson, Proc. Biol. Soc. Washington, xii, pp. 146-147, 
June 3, 1898. 

Type locality. — Escondido River (50 miles above Bluefields), 
Nicaragua. Type no. ||||^ U. S. National Museum, Biological Sur- 
vey Collection. 

Distribution. — Dense humid tropical forests of the lowlands along 
the Escondido River. 

Characters. — Similar to S. cestuans hoff'?nanni but underparts 
more ochraceous and tail washed with dull yellow. Pelage thin and 
soft; tail slender. Teats: p.| a.f. 

Color. — Upperparts, including top of nose and base of tail, nearly 
uniform dark, ochraceous brown, darker on crown and along middle 
of back ; outside of fore legs and feet like sides of neck, and more 
ochraceous than back ; outside of thighs like back, hind feet some- 
times like thighs, but usually more ochraceous; ears like crown, a 
small dingy yellow basal patch sometimes present ; side of head paler 
or more yellowish brown than back, with a narrow ring of dark 
brownish buffy about eye ; underparts varying from dark buffy yellow 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA lOI 

to dingy ferruginous; tail above black, thinly washed with dull yel- 
lowish ; below, with broad median area grizzled yellowish brown, in- 
distinctly and narrowly bordered with black and thinly edged with 
dull yellow. Hairs on back, black with narrow subterminal (some- 
times median) ring of rusty yellow. 

Variation. — The series at hand shows comparatively little variation. 
Four specimens representing the summer pelage (May lo to Sept. 27) 
are rather darker above and dingy ferruginous below. Specimens 
in winter pelage (October to May) have more ochraceous backs and 
yellower bellies. Apparently there is no seasonal difference in the tail. 

Measurements . — Average of five adults from type locality : total 
length 361.4; total vertebrae 169.4; hind foot 51.6. 

Cranial characters. — Premolars y. Skull averaging a little smaller 
than that of S. hoffmanni but otherwise very similar. Five adult 
skulls from the type locality average: basal length 42.1; palatal 
length 22.1 ; interorbital breadth 16.3; zygomatic breadth 30.4 ; length 
of upper molar series 8.3. 

General remarks. — Sciurus rich^nondi bears a general resem- 
blance to S. deppei but is readily recognized by its yellow washed 
tail and single premolar. It differs from the still nearer S. cestuans 
kq^ma?ini of Costa Rica by the yellower back and underparts and the 
slender, yellow washed tail. 

Specimens exat?iined. — Eighteen : all from the type locality. 

BAIOSCIURUS subgen. nov. (p1. I, fig. 4.) 

SCIURUS DEPPEI Peters. Deppe's Squirrel. 

Sciurus deppei Peters, Monatsber. K. Akad. Wiss. Berlin, 1863, p. 654; 
Alston, Proc. Zool. Soc. London, 1878, pp. 668-669, (part; Mexico, 
Guatemala, and Honduras); Allen, Bull. U. S. Geol. Survey Terr., 
IV, p. 885, 1878 ; Alston, Biol. Cent. -Am., Mamm. p. 133, 1880 
(part; Mexico, Guatemala, and Honduras); Sumichrast, La Natu- 
raleza, V, p. 324, 1882 ; Thomas, Proc. Zool. Soc. London, 1890, p. 74; 
Allen, Bull. Am. Mus. Nat. Hist., N. Y., ix, p. 190, 1897. 

Macroxus tephrogaster Gray, Ann. & Mag. Nat. Hist., 3d ser., xx, p. 431, 
1867 (part; Mexico, Guatemala, and Honduras); Ann. & Mag. Nat. 
Hist., 4th ser., x, p. 408, 1872. 

Macroxus tcEni2irus Gray, Ann. & Mag. Nat. Hist,, 3d ser., xx, p. 431, 
1867. 

Macroxus griscogcna Gray, Ann. & Mag. Nat. Hist., 3d sen, xx, p. 429, 
1867 (part: Mexico [and Honduras ?]). 

Type locality. — Papantla, Vera Cruz, Mexico. Type in Berlin 
Museum. 

Distribution.— Yiwn\\iS. Tropical and Austral zones from Truxillo, 



I02 NELSON 

Honduras, northward along mountains on both coasts of Guatemala 
and Chiapas, to the Isthmus of Tehuantepec, and thence along the east 
coast of Mexico to Papantla, Vera Cruz (alt. below 6000 feet, spo- 
radically up to 9000 feet). 

Characters. — Size small ; upperparts dark rufous or olive brown ; 
fore feet and outside of fore legs dark gray in typical specimens (like 
back in others) ; tail above black thinly washed with white. Tail 
slender; pelage soft and rather full ; under fur long; ears long and 
thinly haired. Teats : p. i a. i i. \. 

Color. — Eighteen specimens from near type locality: Upperparts 
including top of nose and base of tail, uniform finely grizzled dark 
rusty brown varying to dull dark yellowish brown ; ears like crown, 
with small basal patch. of white or dingy fulvous; sides of head paler 
and more yellowish than back ; outside of fore legs and fore feet dark 
gray, contrasting with color of back ; outside of hind legs like back, 
with hind feet similar but a little darker; underparts white, or grayish 
white, sometimes buffy on breast and inside of thighs, and color of 
flanks sometimes extending in on inguinal area and inside of thighs ; 
tail above, black thinly washed with white ; below, with broad median 
area varying from grizzled ferruginous brown to dark yellowish bi"own, 
bordered with black and edged with white. Dorsal hairs black, with 
broad subterminal and sub-basal rings of yellowish or rusty brown. 

Variatiofz. — This species presents considerable individual variation, 
but in view of its wide distribution there is remarkably little geograph- 
ical variation. Seasonal changes of pelage are not marked, the only 
notable differences being the frequent absence, in summer, of the ear 
patches and white tip of the tail, which is thus left black. There are 
no signs of melanism. Specimens from the vicinity of Jico and Las 
Vigas, Vera Cruz, and elsewhere in the higher parts of the range of 
the species are considerably larger than those from the low country 
near the type locality, but without accompanying differences in color. 
Specimens from the damp forests of eastern Mexico are somewhat 
darker along the middle of back, with underparts more inclining to 
fulvous than in those from interior and western Chiapas. The series 
from southwestern Chiapas, and a specimen from Truxillo, Honduras, 
are more olivaceous above and clearer white below. A specimen from 
central Guatemala (Coban to Clusec) is decidedly darker and more rusty 
above and below than the average, but other Guatemala specimens are 
nearly typical. Most specimens have the underpai'ts soiled whitish or 
grayish, but there is every gradation through pale buffy to dark fulvous 
and rusty rufous. A Verreaux specimen (no. -jV^y U. S. National Mu- 



SQUIRRELS OF MEXICO AND CENTRAL AMERICA IO3 

seum) , labeled ' Mexique ' is dark rusty red on chest and middle of belly. 
A half-grown specimen from Catemaco, Vera Cruz, has the middle of 
back darker than usual, the chin dingy white, rest of underparts deep 
rusty fulvous, and the usual white tips of hairs at end of tail replaced 
by rusty fulvous. A specimen from Ocuilapa, Chiapas, has the under- 
parts, outside of thighs and hind feet washed with ferruginous. One 
from west-central Vera Cruz has the underparts plumbeous gray with 
a faint whitish wash. Specimens from the region of the type locality 
usually have the outside of fore legs and fore feet finely grizzled dark 
gray, contrasting with back, but in those from farther south the color 
of the back usually extends over this area. 

Measure77ients. — Average of 5 adults from vicinity of type locality : 
total length 384; tail vertebrae 182.4; hind foot 54.4. Average of 
five specimens from just below Las Vigas, Vera Cruz : total length 
393,9; tail vertebrae 173.4; hir^d foot 57.5. 

Cranial characters. — Preniolars \. Skull (pi. I. fig. 4) in general 
like that of 6". hoffmanni but proportionally more slender and other- 
wise distinguished by the small upper premolar and longer audital 
bullae. Skulls from Jico and Las Vigas, Vera Cruz, are sometimes 
larger than ordinary specimens of S. hoffmanni but the differences in 
proportion remain the same. Four adult skulls from the vicinity of 
the type locality average : basal length 42.5 ; palatal length 21.6; in- 
terorbital breadth 15.2; zygomatic breadth 28.6; length of upper 
molar series 9.3. 

General ?iotes. — Macroxus tephrogaster is unquestionably a syn- 
onym of Sciurtis deppei. In the original description of AI. tephro- 
gaster Gray mentions specimens from Mexico (Salle), Guatemala, 
Bogota and Honduras. Mr. Thomas writes that the Salle specimen 
from Mexico (B. M. 56. 8. i. 11) may be taken as the type, since it 
agrees exactly with Gray's description. A nearly typical specimen of S. 
deppei from Jico, Vera Cruz (no. 54,981, U. S. National Museum) 
was sent Mr. Thomas, who writes that it " matches the type of teph- 
rogaster and may be accepted as typical." This proves beyond ques- 
tion that 5. tephrogaster is a synonym of S. deppei. Mr. Thomas 
also writes that the type of Macroxus tceniurus Gray described from 
Guatemala, differs from a specimen of S. deppei (no. 63671, U. S. 
Nat. Museum) from Motzorongo, Vera Cruz, only in having the chest 
and belly washed with yellow — merely a matter of individual variation. 

Habits. — This species lives in dense humid forests and passes 
much of its time seeking food on the ground. It is quiet and not often 
heard, though now and then one will chatter and scold at an intruder. 



104 NELSON 

In some places it is very abundant, notably on the east slope of the 
Cofre de Perote above Jico, Vera Cruz, and on the mountains above 
Tapachula, Chiapas. 

Speci?nens examined. — Seventy three : from Papantla, Jico, Las 
Vigas, Jalapa, Cordova, Motzorongo and Catemaco, Vera Cruz; 
Metlaltoyuca and Huachinango, Puebla ; Reyes and mountains near 
Santo Domingo, Oaxaca ; Ocuilapa, San Cristobal, Pinabete and 
Tumbala, Chiapas ; Coban to Clusec and central-western Guatemala ; 
Truxillo, Honduras. 

SCIURUS NEGLIGENS Nelson. Little Gray Squirrel. 

Sciurus arizonensis Alston, Biol. Cent. -Am., Mammalia, pp. 125-126, 1880 

( part : from Tampico, Tamaulipas, Mexico ). 
Sciurus deppei K\x.'£.-ii, Bull. Am. Mus. Hist., N. Y., iii, p. 222, 1891 (part : 

from Valles, San Luis Potosi ; and Victoria, Tamaulipas, Mexico ). 
Sciurus negligens Nelson, Proc. Biol. Soc. Washington, xii, p. 147 June 3, 

1898. 

Type locality. — Alta Mira, Tamaulipas, Mexico. Type no. 93028 
U. S. National Museum, Biological Surv'ey Collection. 

Distribution. — Arid tropical forests of lowlands in extreme north- 
ern Vera Cruz, eastern San Luis Potosi, and southern half of Tam- 
aulipas, Mexico (below 1000 ft.). 

Characters. — Size of S. deppei ; ears longer and dull rusty ; upper- 
parts rather pale grayish brown ; underparts white or pale buffy yellow. 
Pelage soft and rather thin ; tail thin and slender. Teats : p. f 

a. y 1. y. 

Color. — Upperparts, including top of nose and base of tail, rather 
pale, finely grizzled grayish brown, generally with a slight yellowish 
or dull rusty suffusion, most marked posteriorly ; sides of head and 
neck, and sometimes nape, dingy yellowish brown ; ears varying from 
dingy rusty to dark ferruginous; a small dingy white basal patch 
usually present ; fore feet, outside of legs, and sometimes adjacent part 
of shoulders, dull gray ; outside of thighs and hind feet usually like 
rump, but toes sometimes gray ; underparts white, varying to uniform 
deep fulvous or almost rusty yellow ; inside of thighs pale buffy in 
white bellied specimens ; chin and throat usually white ; tail above 
black, thinly washed with white ; below with broad median area 
grizzled and varying from yellowish to grayish brown, bordered by a 
thin line of black and thinly edged with white. Hairs of back black, 
with narrow subterminal and sub-basal rings of yellowish gray or yel- 
lowish brown. 



SQIJIRRELS OF MEXICO AND CENTRAL AMERICA IO5 

Variation. — The main variation is in the amount of rusty on the 
ears, and in the color of the underparts, which ranges from white to 
deep buffy yellow. Some specimens are considerably grayer above — 
less shaded with yellow — than others. No melanistic specimens seen. 
Spring and autumn specimens show no seasonal differences. 

Measurements, — Average of five adults from type locality : total 
length 3S7.4,; tail vertebras 188.3 ; hind foot 54. 

Cranial characters. — Premolars f . Skull indistinguishable from 
that of typical 5". deppei. Four adult skulls from type locality aver- 
age : basal length 41.7; palatal length 21.4; interorbital breadth 15.3; 
zygomatic breadth 28.4; length of upper molar series 9.1. 

General notes. — Sciurus negligens closely resembles S. deppei in 
size and general appearance, and inhabits the more arid country lying 
north of the region occupied by the latter species. It is readily dis- 
tinguished from S. deppei by the much grayer color of the upperparts. 

Habits. — These squirrels are most numerous in the stunted forests 
of ebony, 15 to 25 feet high, which cover great areas in their range 
and furnish their main food supply. We found them in the greatest 
abundance at Velasco, San Luis Potosi, where the ground under the 
trees was strewn with gnawed seed pods. 

Speci?nens examined. — Twenty-three : from Alta Mira and Victoria, 
Tamaulipas ; and Velasco and Jilitla, San Luis Potosi. 

Subgenus MICROSCIURUS Allen (p1. I, fig. 6; p1. II, fig. 2.) 
SCIURUS ALFARI Allen. Alfaro's Pigmy Squirrel. 

Sciurus {Microsciurus) al/ari AiAJK^i, Bull. Am. Mus. Nat. Hist., N. Y., 

vii, p. 333, Nov. 8, 1895 ; Ibid., ix, p. 35, 1897. 
Sciurus alfari Alfaro, Mamiferos de Costa Rica, pp. 31-32, 1897. 

Type locality. — Jimenez, Costa Rica. Type no. VA"» Ameri- 
can Museum of Natural History, New York. 

Distributiojt. — Dense humid forests of northern, eastern and south- 
western Costa Rica. 

Characters. — Size very small ; ears short and rounded, upperparts 
dark, minutely grizzled reddish brown, the reddish most intense on 
nose and sides of head ; ring about eye reddish buffy. Pelage soft and 
dense; tail slender. Teats: p. y a. i i. \. 

Color. — (Of type) : Entire upperparts including ears and outside 
of legs, minutely grizzled dark brown, suffused with dull rufous ; rufous 
most intense on head and brightest on narrow ring about eye ; feet 
and toes grizzled rusty brown slightly paler than back ; chin, throat, 



I06 NELSON 

chest and inside of fore legs pale dull ferruginous, shading posteriorly 
into dark brown, with only a slight wash of reddish along middle of 
belly and inside of thighs ; tail at base like back ; remainder of tail all 
around, grizzled dark reddish brown and black with fine yellowish 
brown tips to hairs; hairs of extreme tip forming a black pencil. 
Hairs on back black with narrow subterminal rings of rusty yel- 
lowish. 

Variation. — Two adults, including the type and one partly grown 
young, show but little variation except in color of underparts. The 
immature specimen is slightly more reddish on back and tail; the 
cheeks, chin, throat, chest and line down middle of abdomen are dark 
dull ferruginous, and the sides of abdomen are similar to flanks. The 
other adult is like the type except in the dull brownish buffy of the 
underparts. 

Measurements. — Average of two adults (from dry skins) : total 
length 251 ; tail vertebriE 109; hind foot 37. 

Cranial characters. — Premolars \. Skull (pi. I, fig. 6; pi. II, 
fig. 2) short, broad, and much arched over top of braincase, the con- 
vex outline descending in an almost unbroken curve to edge of occiput ; 
rostrum short and broad, especially at base where the upper parts of 
the premaxillaries are very broad and heavy; jugals very broad verti- 
cally, much more so than in the other species examined in this sub- 
genus. Measurements of type skull : basal length 29.5 ; palatal length 
14.2; interorbital breadth 13; zygomatic breadth 22; length of upper 
molar series 6. 

General notes. — Little is known about the interesting squirrels of 
the subgenus Microsciurus., but, as suggested by Dr. Allen, further 
work in Central and South America is revealing other species. Mr. 
Cherrie collected the type in the forest on the slope of the Volcano of 
Turrialba, near Jimenez, Costa Rica, and the species has been found 
since in several other parts of the country. 

Specimens exatnined. — Three : from Jimenez, San Carlos, and Re- 
ventazon, Costa Rica. 



PLATE I. 



Skulls of 9 subgenera of Tropical American Squirrels. 
[Natural size.] 

Figs. I. 5. {Parasciurus) ludovictanus limitis. Kickapoo Springs, Texas. 
(No. ^Vo?"? ad. U. S. Nat. Mus.) 
2. 5. {Oioscturus) durangi. El Salto, Durango, Mexico. 
(No. 94580 $ ad. U. S. Nat. Mus.) 
5. {^Arceosciurus) octilatus. Las Vigas, Vera Cruz, Mexico. 

(No. 54238 $ ad. U. S. Nat. Mus.) 
5. (^Baiosciurus) deppei. Huauchinango, Puebla, Mexico. 

(No. 92998 9 ad. U. S. Nat. Mus.) 
5. {Hesperosciurtis) g-riseus. Trout Lake, Washington. 

(No. 89006 9 ad. U. S. Nat. Mus.) 
5. {Aficroscturus) alfari. Jimenez, Costa Rica. 
(No. 9554 $ ad. Am. Mus. Nat. Hist.) 

7. 5". ( Guerlingtietus) cestuans hoffmanni. Talamanca, Costa Rica. 
(No. 2811 $ ad. Am. Mus. Nat. Hist.) 

8. 5. ( Tamtasciurus) douglasi tnearnsi. San Pedro Martir Mts., Lower 
California, Mexico. 

(No. 25170 ad. U. S. Nat. Mus.) 

9. 5. {^Echinosciurus) aureogaster. Alta Mira, Tamaulipas, Mexico. 
(No. 93034 9 ad. U. S. Nat. Mus.) 

(108) 



Proc.Wash. Acad. Sci., Vol.1. 



Plate 




Skulls of Mexican Squirrels. 



Heliotype Pnntin| Cci,Btislon. 



I 



PLATE II. 

Skulls of Tropical American Squirrels. [Natural size.] 

Figs. 1. 5, {Ecfiinosciurus) boothice belti. Escondido River, Nicaragua. 
(No. 48847 9 ad. U. S. Nat. Mus. ) 

2. 5. [Microscturus) alfari. Jimenez, Costa Rica. 

(No. 9554 9 ad. Am. Mus. Nat. Hist.) 

3. 5. {Echinosci'urus) poh'opus. Cerro San Felipe, Oaxaca, Mexico. 

(No. 68183 ? ad. U. S. Nat. Mus.) 

4. iS". [Hesperoscturus) griseus. Trout Lake, Washington. 

(No. 89006 9 ad. U. S. Nat. Mus.) 

5. 5". [Echinoscturus) boothice belti. Escondido River, Nicaragua. 

(No. 48847 9 ad. U. S. Nat. Mus.) 

6. 5. {Echtnosciurus) thomast. Talamanca, Costa Rica. 

(No. 23367 ad. U. S. Nat. Mus.) 

(no) 



pROC. Wash. Acad. Sci., Vol.1. 



Plate II 









Skulls of Mexican Squirrels. 



Heliotype Printing Ca.BMton. 



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